Originally Posted by v2win
I would pull a motor and trans from a junkyard and rebuild that as you have time. The cost to rebuild is going to be close to the same.
There are some differences between the two if you go with a 360. The 318 is balanced internally and the 360 is balanced externally so the torque converter is different as well as a different flex plate.
The heads on the 360 flow a little better and respond to port matching and cleaning up the bowls really well with a cam swap.
don't forget the harmonic ballancer will need to be matched tot he 360 as well, if you get a junk yard 360 they may strip it off the 360 and you will be screwed with out it.
harmonic ballancer, tourque converter, flex plate, all direct bolt all need to be swapped out to match the 360,