Finally making some progress.
The throttle body and adapter plate was a ton of work to get right. The 454 tbi unit I got off ebay needed the throttle shaft fixed, ended up being a bigger job than I anticipated, but turned out great, actually ended up silver soldering material onto the shaft and turning it back to size to match the housing. I did this because the bores in the housing were nice and round, the shaft on the other hand was all worn out and needed to be replaced or fixed so I just did all the repair on the shaft and left the housing alone.
Then the holley 17-45 adapter plate I got from Summit came and when I bolted the tbi unit to it the throttle bores were off from the holes in the adapter plate by .10". Not sure what the deal was on this?? so I ended up plugging the existing holes with 1/4" pipe plugs and refacing the plate and putting the new holes in the proper spot. Lines up perfect now and I also put some alignment bushings in the aft two holes. The tbi was already counterbored for these from the factory, this makes it nice to line things up, gaskets, etc.
Also did a bunch of blending work on the adapter and performer manifold to get them all to flow nice together. Lots of work but it turned out the way I wanted it.
Also finished up the Megasquirt water tight case and tested it out on the bench, all circuits performed as expected. Going to mount the ECU on top of the driver side inner fender well in the engine bay.
Next step will be installing the ECU and working out the crank trigger, fuel supply, throttle/kickdown linkage and the wiring harness. Fun stuff
P.S. Still looking for an ignition timing map if anyone has anything to start with? thx