Thanks. It's just the intake. Long block is GM crate 300/350.

Sounds like the optical / magnetic VSS bit? Optical sensor produces 2k square wave 0-5V. Easy solution if you have the right signal.

Not quite tuned port, but this 89 GMC was switched to 7730...

It does seem a bit backward to repin for 7730 when 7427 can do the job but I understand KISS in configuration. I have repinned a 7747 truck to 7730 but I think I'd probably build a conversion...