The intake manifold is probably from a 1991-1993 Caprice, or Roadmaster or Olds Custom Cruiser. Those cars used TBI but they also had excessively large cowl overhangs that extended over the area of the distributor. The factory had to oversize the distributor hole in the intake to allow removal/replacement with the intake still mounted on the engine.

That intake can still be used but you need a distributor from any 1991-1993 fullsize GM car with a v6 or v8. OR you need a different TBI intake from an Fcar or from a C/K/G truck/van that had TBI.

See also this thread:

http://thirdgen.org/techbb2/showthre...butor+hole+TBI

HTH.