68 318 or 79 360

Will the truck 727 work if it was only a 2 wheel drive, and will it be the same length of one that was made in 74? Reason I ask is the donor car I found for the drive shaft and rear end is a 74. It has a 727 and an 8 1/4 I want to use in my Duster to replace the 7 1/4. I plan on buying headers for the car so not worried about exhaust manifolds. Someone mentioned B&M Flex plate? if I used the truck trans would I need it, or I couldn't use the truck trans and would need the B&M flex plate to use a car 727 on the truck motor? Both engines are $200.00