Welcome to the board Steve...
Might help to tell what type of ignition is (or should be) on the 350/355?... where the engine came from... (heck, even though it won't matter for your question, I'm interested in what axles... and which New Process t-case is going in...
)
I'm assuming that you're interested in modifying the stock wiring harness to some other EFI?? Am I close?
DodgeTruggy had "great success" in mangling his wiring until having someone else fix it -- after giving up.. hahah
To be clear, I'm probably not much help, just trying to get some more info for those that might be...
Welcome again, enjoy your stay...