I have a question about two combinations I have. The first is a 400 block 4.375 bore by 4.25 stroke I forget the rod length by they're bb chevy. It revs hard and runs good with eddy heads and a hyd cam 10.60's. I bought a 511 440 block with 4.350 bore 4.300 stroke with 7.100 rods. Its set up for boost so its only 8:1 and has a blower roller in it. Has 440-1 heads. I want to change the pistons and cam to run NA. Probably have the heads cnc ported too. What do u guys think of the rb block combo? Are there shelf pistons for 4.350x4.300 stroke w7.100 rods?

I think most feel the stock 440 block is good for about 650 hp. Over that I would consider aftermarket block. I use a 440 block in my mild 493 but I only make about 600 hp. Ron

I say you already have one great running NA 511, save the new one for a Turbo.

Why change pistons and cam to make another NA. If its the 440-1 heads you like vs the Eddies , switch them.

If you need two, great running 511 NA motors, then yes change the cam and the pistons. Not sure about off the shelf pistons per your request. Others will know better.