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a cheaper alternative might be to get a 4.15" cast stroker crank.

kb-silvolte.com shows the #1271 piston (for a 383) as a 1.848" comp height.

1.848+6.76+(4.15/2)= 10.683", or .042" in the hole based on the blueprint height of 10.725" for an RB block.

based on my calculations assuming a .040" head gasket and 88cc heads, you're looking at about 9.96:1 compression

use a largish cam or a wide LSA to make the intake closing point late to bleed cyl pressure, and it should run on pump premium.

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better check your math
1.848 + 6.76 + (3.75/2= 1.875) = 10.483 - 10.725 = -.243
About 7 to 1 compression give or take

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The 383 pistons in the 426 that are in there now are about .200 in the hole. I spoke with Dave at Hughs Engines and he figured the correct flat top pistons that they sell at .030 over would come in at about .060 in the hole. With the 452 heads it should be about 9.1 to 1 compression. This is by his figures. This would be great for me being that the car is strictly a cruiser and for touring with the car club. He said I could do better by using a thinner head gasket.
I wonder if it would be better to use the 516 heads that I have on the shelf?
Thanks all, Alex

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Either way you have no quench , the 452's will flow better than the 516's .

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This is where I get totally lost. This "quench" thing everyone keeps bringing up. So what happens when there is no quench and how do I get it. How can I not have it if I'm using just stock type parts??? Is there somewhere that I can read about to get an understanding?
Does not having quench lead to pinging in the motor? Thanks, Alex

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Quench wasn't a big deal when you could buy hi octane fuel at the pump on any street corner for pennies a gallon , now it's what you need to achieve if you wnat optimum performance to run on the piss available on every street corner.

Yes it can lead to detonation (pinging) especially with higher compression ratios .

What you want is .040-.045 between the piston and the head on the side of the chamber away from the valves , to achieve it with open chambers leads to aggressive head milling or step dome pistons , with closed chamber you want the piston no more than .020 below the deck with a steel shim gasket or zero deck with a composite gasket and a closed chamber head.

I have 2 friends with almost identical built 440's both using the same cam and 906's, one with KB step domes and .060-.065 quench distance , his compression ratio was 9.3 and it would ping with anything less than 93 octane , other was a motor I did a lot of machining to achieve .040-.043 with the same step dome pistons. The heads were something I had bought from another member with big valves and milled about .050 initially and compression ended up about 10.3, this one ran with no pinging on 93 octane with 38 degrees total timing.

As far as why you don't have it using stock type parts , mopar didn't do anything to really achieve it so it's a mix and match to get it if possible , unfortunatley you are working with something you can't mix and match with .

I don't know what hughes has for pistons but to get it with your 452's will be impossible without a custom piston , which is easily doable. I'm getting ready to have a set made up by diamond and it's not as pricey as you would expect for a 440 build I'm doing using 452's. Or you need a flat top with about 2.060 CH , that'll be .020 in the hole on a 10.725 deck , steel shim gasket and a closed chamber head of your chosing .

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The 383 pistons in the 426 that are in there now are about .200 in the hole. I spoke with Dave at Hughs Engines and he figured the correct flat top pistons that they sell at .030 over would come in at about .060 in the hole. With the 452 heads it should be about 9.1 to 1 compression. This is by his figures. This would be great for me being that the car is strictly a cruiser and for touring with the car club. He said I could do better by using a thinner head gasket.
I wonder if it would be better to use the 516 heads that I have on the shelf?
Thanks all, Alex

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I just ran this setup with the hughes engine piston thru a calculator , Dave is correct , you'll have 9.1ish compression , no quench , you can run that and with the right tune it won't be a pinging pig , this is using the 452's , the 516's will bump the compression closer to 10.0 , you may have issues but with a custom ground cam and the right tune you should be ok , but you'll give up a little because of the lack of quench , to get it would require cutting .040 off the block which I highly do not recommend as the machining cost will get you up to having Diamond make you a better suited piston .

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John, In my other car I have a 440 block that I put in sixpack pistons and sixpack rods. I'm using 452 heads on this motor and I do have pinging at higher rpms. More noticable when I get on it. Would a different set of heads do better on this motor?Like 915s? I always hated hearing the pinging!!!

Going back to the 426, can you tell me what specs I would need to order custom pistons for this engine to make it right? Thanks, Alex

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John, In my other car I have a 440 block that I put in sixpack pistons and sixpack rods. I'm using 452 heads on this motor and I do have pinging at higher rpms. More noticable when I get on it. Would a different set of heads do better on this motor?Like 915s? I always hated hearing the pinging!!!

Going back to the 426, can you tell me what specs I would need to order custom pistons for this engine to make it right? Thanks, Alex

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Are you looking for a set of old standard bore pistons, flat tops? I also know where there is a set of 70 over hi comp pistons. Or even some real old TRW 60 over 13.5 pistons.