When I swapped a carbed 5.9 into my '88 Dak (originally 4 cyl.), I had to overcome just the opposite- no juice for ignition at starting. The wiring for the keyswitch did not allow for the normal "IGN 1" and "IGN 2" scheme, so I had to wire a relay into the starter relay (had to use a relay to avoid backfeeding the circuit) to supply power to the "start" side of the ignition circuit.
Some of the circuitry changed between the 4 cyl. and V6/V8 models, but you may have a similar situation, only the opposite...?