The difference in the engines compression ratios did not come from being machined differently----------the oem manufactures open up head chamber cc and used severely dished pistons to lower the CR so the low octane lead free gas could be used----------for the results that you are looking for you can probably source an rebuild kit from source like perfit circle or sealed power----------kits are available with pistons,rings,bearings,gaskets plus you can choose various cam/lifter set ups-----------


If I was building a street type 350 (even a stroker) I would use one of the later blocks (one piece seal ) for the roller lifters-----


I would also mention/suggest that you look at the possibility of swapping in one of the late model LS series engines from a wreck car