68 Cuda 383 vs a 360

Usually the piston manufacturer will makea few changes forlittle to no cost. The last set of 4.375" 1.320 CH pistons I had with upgraded pins and hellfire rings were 3-400 more than the same pistons with standard pins and moly rings.

A few weeks ago I recieved a quote from RaceTech for a set spec'd identical to the Diamonds. $1400 rated for 400hpshotof NOS or 15psi boost.

I would not mess with the ring pack on anything less than a race engine. With a .017" ring pack a vacuum pump would most likely be required.

Not sure I would use a 4.25" bore block for anything other than class racing or a resto these days. Basically if you need anything that requires more than a 2.14" intake valve you are in 400 440 territory.

For instance, on a 4.375" bore 400 block a 2.30" intake valve hits the opposing cylinder wall at a little over .800 lift. 2.250 valve no problem. My point is that bore size is very relevant to valve size and cam spec. The larger bore engines avoid some of these headaches IMO.