What is your budget? IMO, it is really hard to tear into a short block, change a bunch of stuff, and come out on the cheep.

OK SUPER LOW BUCK DEAL. basically stock '76 400, runs well, doesn't smoke but low on power. I want to do nothing more than swap out the low compression pistons for some KB240 ones, I do not want to do this if it needs to be bored oversize, I do not want to do any thing other than bump the compression.

QUESTION....when the heads come off, with a dial/bore gauge what is the maximum the cylinders can be to use standard bore pistons /rings???

If it has too much wear and needs to be bored, I will not take it apart father and it will go right back together.

If I can go the route of new pistons, I will mill the heads and deck the block only minimal to clean-up the surfaces, and be able to use fel-pro composite gaskets and gain cc's

my experience with the kb's i've used is that the bore size needs be on the money to achieve recommended clearance. .001"-.002" larger and they're pretty noisey, in fact they're a little noisey cold at .002"-.0025".

If I can go the route of new pistons, I will mill the heads and deck the block only minimal to clean-up the surfaces, and be able to use fel-pro composite gaskets and gain cc's

Where is Dan when you need him ??

You are going to do ALL that and you can't come up with MAYBE another $300 to BORE it ... seriously ???

Ignore the ridge reamer recommendation , if you don't know what you are doing with it then you will do more HARM than good to the block.

I have personally been burned by someone that didn't know how to use one ... had to sleeve a block because it took .075 overbore to get a clean pass, top to bottom, on one cylinder , .040 on the one next to it , the 2 next to those at .030 , the other side would have cleaned at less ...

i didn't know people used ridge reamers anymore.

If its a OLD block.. they were soft(before they
started putting more nickle in them) you HAD to
use a ridge reamer to even get the piston out of
the bore.. yeah I still own one somewhere around
here but havent used it in over 20 years(maybe 25)

If you're not boring or power honing the cylinder then ignore the recommendation to ignore using the ridge reamer and use the ridge reamer. It's not rocket science. You may be able to rent one from an auto parts store.

If the new top compression rings run up and over a ridge at the top of the cylinder, even after use of a ball or three finger glaze breaker, it will destroy the new rings and pistons. Even if you use the same piston it will destroy the rings and piston because the new bearing raises the piston height in the cylinder, even thought it's only a thousandths of an inch.

Removing the ridge isn't just for ease of piston removal.

It's easiest to use before piston removal because you can square the tool on top of the piston. It's not rocket science unless you're the guy that screwed it up for JohnRR, and the instructions are an easy read.

i was thinking about a 360 i put together. this was 100,000 mile dakota engine. always unleaded fuel and the oil changed religiously. from what i can remember running a dial bore gauge thru the cylinders that there was next to none taper! that 400 may not have a ridge; if taken care of.

I bet the moly rings, harder block and superior efi fuel control had something to do with that.

Every block I had come into the machine shop where I worked that had a ridge reamer used on it was screwed up. Not all, but the vast majority of people will remove way too much material from the bore w/ a reamer.
I've taken a lot of motors apart that had big ridges and never used a reamer. Not worried about saving the pistons, so I just knock em out. If it has a big ridge, the pistons shouldn't be getting reused.