if you do not have a crank or pistons why not bore it to 4.500 and stroke to 4.250 4340 crank use a .250 longer rod h beam s .use srp.s pistons. flat tops. rings i would use are je rings .cam roller mechanical 685/685 269/276 on lobe sep 114 bearings federals 3/4 mains races bearings. the fed s keep the oil flim when increased load capacity this would be a540 and make 650 with out a blower and with 800+ heads gm rect ports 990.this is very close to what i have in my 50 chevy coup street car and it is fast fast fast if you do not like braking tires loose at 110 do not build it you will need bf goodrich radials and put a ford 9 inch and a good 400 trans you will need it .and msd 6btm box put a drive shaft loop in it this would 9 to1 so you will not need much boost run 110 fuel