OK then its HEI. Very simple very reliable. Does not rev beyond 6500 reliably.
You could hack the wiring harness or just gut the harness and build new.
In my experience modding a stock harness is the path to hell.
I fix lots of broken race cars that have these issues, as well as offroad rigs.
Most stock harnesses have too many wires... :)
I seem to recall that painless sells a Chevy specific kit that deletes the
engine compartment wiring harness and it plugs intot he existing bulkhead
connector on the fire wall.
Painless gets about 550 for a full harness for a fuel injected V8
package, but they are running a 100 dollar rebate.
Google painless wiring and follow it I'd call them and see what
they have for your engine and chassis.
Worst case maybe you can find a mini kit to just get your engine spining.. :)
Dave