Well if my guess is right and remember this is just a educated guess with a little research
i would keep the crank because i believe it has a longer stroke i would keep the piston because i believe it has a larger bore and a higher pin height as needed because of the longer stroke crank the same deck height block as the 390 and the same length rod as the 390 and i would keep the block and side cover only because its bore matches the piston now you have a bored and stroked 390 now seeing as how it has the stock length rod you can now use the arc billet rod then replace everthing else with honda parts or after market performance parts of course i could be completely wrong
please dont waste your money based on my gut instints :laugh: