Dumbest thing yet. When I re-installed the starter I had put the power and ground lines on the same post. Ugh! Sorted quickly and not it lives again.
On a bright note, the Ford starter relay fits in really well, easier than I expected and bolted to the stock mounts with a tiny mod. This one should never burn out, but if it does I can get one anywhere for $12. I have it all together and running for tomorrow's ride but I'll be taking it apart and rewiring it cleanly. Better cable ends and probably replace the stiff OEM battery cables with some larger, more flexible ones.
Scott