Most improtant update so far, besides the CRT still being under vacuum: the proto chassis passed it's first signal tonight!
Yes it was a hacked together mess, no it was not pretty. But it did the trick!
I cobbled together the B+ supply, powered only the filaments of the tuner and IF, then slowly increased the variac till 200 volts showed on the meter. Then I glanced over at the scope, and what do I see? A messy luma staircase at the grid of the 1st video tube! It looks like hell, but the important thing is it's there. There was no AGC voltage applied, so that's probably why the signal was all dirty.
Work today sucked, but this more than makes up for it.
Tomorrow I figure I'll try to add some AGC voltage since I know where the AGC buss is located, to see if I can't get the signal to look better. Hope it works.