Whatever dual plane 4 barrel intake you can lay your hands on stock or otherwise. With no head work there is no need to get carried away with big induction or big anything else for that matter.

MP performance or reworked mechanical advance distributor with an appropriate curve in it.

Did the 5.9 magnum have a roller that is compatible with the 318 valve train? If it's bigger than the 5.2 cam, it should be cheap and better. If not that then a reground OEM cam.

Swap meet headers and dual exhaust.

A B-body 8.75 can be coaxed into the existing spring spacing or maybe an 8.25 with a SG for cheap. 3.55 max.

904 (998?) trans with the low gearset and if Dwayne's dyno sheet is any indication, a good converter (3800-4000?).

Throw all the chassis tricks in the book at it to help the little engine that could hurl it out of the hole and if all else fails, blue bottle in the trunk.

Kevin