Sounds like you are on your way to being sorted Pete
Just for info for anyone interested, as far as disc brake options, it used to be that the 73-76 disc spindle (i.e. big inner bearing) and 11.75 disc was the only cheap route to go. The caliper adaptors were readily available in the US from the later c-bodies and the spindles were not too difficult or expensive to find. All assuming you lived in the US or were resourceful of course!
Then the prices started going up - the adaptors used to go for $20-30 a pair, I got mine for $50 a few years ago and at the time rued missing the earlier cheap deals! Now I see they are over $100! Also the spindles went up in price.
Of course that eventually led to two things - the aftermarket reproducing the spindles (and I think someone does the adaptors now too - at least as part of a kit), and also other cheapo alternatives surfacing e.g. use of the taller 'plentiful' F/M/J spindles, and a bunch of aftermarket kits using the also plentiful drum spindles for a disc kit. And although they started high, prices seem to have come down to where you can get a complete bolt on kit for decent money, or most of the components or other kits to achieve the same end.
So now there are many options to get to discs, seems to be a new one every month!