Steve, as far as I know the 1975 up 250 and 292 HEI distributor should drop in. The 75-77 distributors had a divorced coil and a short cap, and 78' up had the internal coil like the V8 HEI. Some of the later ones also had ESC(electronic spark control) with the extra 4 wire connector and no vacuum advance. The ESC distributor can be used, just eliminate the ESC by using the module, pick-up coil and vacuum advance from an early distributor. Hope this helps.
OldTruckNut
