all poly 318's had the 727.
it is neutrally balanced.

any small block will bolt up, but only neutrally ballanced motors will bolt up without any extra parts.

for instance the magnum 5.9 bolts up, but you need a special balanced flex plate for it to work, or you need to add weights to the torque converter.
5.2 magnum is neutrally balanced and would bolt right up with the approprate magnum flex plate.

the LA 318 would bolt up with no extra parts.

and you would have 1 bolt hole on the driver side that doesn't line up.

since it is a regular 727 not cable, any 66 and up 727 will bolt up and use the same linkages, so you could take any motor and transmission set and bolt it in. including BB.

just depends on what you are trying to save/keep.