Not a 250 in my '68 Stepside, but a 292 -- however the principles are the same. I bored the original block .030 over, added a Crane 260H cam, Offy 4 Bbl intake, Edelbrock 500 CFM carb, Clifford headers, Centerforce II clutch, "H" pipe, dual exhaust, SM465, 12-bolt 3.73 w/ Eaton posi, 235/85/R16LT Dunlops. I'm pretty happy with the results.