What engine to use

i also have a 68 dart HDT with the slant 225. also i want to make it into a pro-touring car! when i started it was split between a turboed SL6 or a 340 motor.

i am going with the SL6. even tho they weight almost the same u can get an easy 1HP per CI N/A! then if u turboed it u could get 2HP per CI and get 25 mpg to boot!

just an idea