I have to agree with Marc here. I'm not real familiar with the Olds 307, but I know the Chevy 307 is a DOG. It has the same dimensions and weight as the other chevy small blocks (302, 305, 307, 327, 350, 400), which are basically just different combinations of internal parts, but was one of the weakest and least popular motors. If you insist on the GM V8 conversion, spend a couple hundred bucks and pick up a 350, which can EASILY be made to put out over 350 HP! I do however think that any of these would make for a car with horrible weight distribution and possibly severe understeer. Following Marc's suggestion with a smaller engine (4 or 6 cyl) and possibly a turbo, you could feasibly end up with much more power than the D came with and a weight distribution equivalent to the original or even closer to 50/50. I know the offer of the free motor is tempting, but the hastles it will create will quickly negate any savings. Steve VIN 2650