All of the 400 blocks have a lot better main web in them than any of the 440 do That is the main reason I like to start with 400 block for a stroker motor if I have to use a stock block The after market blocks are a lot better, if you can afford to use them

I have had 4 stroked 400 combos so you know what my answer is. The 451 in my 3100lb Demon went 10.07 with max wedge ported Indy SR's. My 69 Charger went 12.07 with a Eddy Rpm Headed 451. Demon went 9.56 with a 400 based 512 with the same Indy heads and same cam. I was lucky and found a 230 casting number block for the Demon. I put a 512 in the Charger and it went 11.39 with ported Edelbrocks Heads and a garbage converter. 1.72 60' Time!!!! All of these passes are at a track with 2200 feet actual elevation. The best corrected altitude was around 3300 - 3400 feet.

As you can see I am a fan of the 400 Stroker!

I agree the 400 has the best main webs but I think up to about 600 hp the 440 will work fine. I am using a 440 block in my 493. I went with the 440 block because I may go to the crossram one day as the crossrams are made to fit the 440 block. But mine has been holding up great for the two years its been in my 63. I race it sometimes and drive it all the time. I figure its making close to 600 hp at the flywheel and about 525 at the wheels to run 10.70's so far at 3700 lbs. Ron

600hp w a 440 block is a time bomb.I saw 2 diff ones blow in one year...they did beat on em,but who doesn't.400 block is the real deal.JMO

The 2 that i saw blow up,did it right along the pan rail.The other one split almost right down the center.

Partial fill, studs, and a girdle..... I would think that a 440 block set up like this should be fine up to 600.

I run a studded 230 casting 400 block. I'm only making around 510 hp though. I figure if I ever rebuild the top end to make more beans, I have a block I can work safely with.