Looks Like I Picked The Wrong Week To Quit Sniffing Glue / '64 Valiant Troubles

I wouldn't do anything based on one compression test. A poor-man's test is to turn the engine over by hand, by pulling & pushing the fan belt. Mark the crank w/ chalk. If you feel 3 strong resistances each revolution, for 2 revs, you know all cylinders are fine. A quick way to test a junkyard engine, and even better than a cranking compression test. You could even find which cylinder is bad that way. Problem is, a slant can still be fairly OK and flunk that test. It will build enough compression at higher rpm and with oil coating the rings. In really good engines, you can hear the cylinder pressure leak off over 10 sec as you turn the crank.

How did the #1 cyl spark plug look? If real clean, like washed with raw gas, the compression might be so low it isn't firing. I had that in my 69 Dart. I recall it read ~70 psi. I jury-rigged it to disable that cylinder by removing the lifters and pushrods, which you can do with the valve cover off. While bragging at my cleverness, a hot-rodding co-worker said I would lose oil pressure with the lifters out, so I made short "pushrods" out of copper tube, with a spring so they held the lifters down, but didn't open the valves. I recently heard that slants (at least solid cam ones) don't have oil passages in the lifter bores, so no problem running without a few. I later put a new long block in my Dart and rebuilt tranny, ran great until stolen 2 months later and never recovered except the license tag.

Most people would just tack weld the upper ball joint back in (common repair), without removing the UCA. Most likely the threads were stripped long ago by a clueless mechanic who thought it was a pressed-in type and the failure was just waiting to happen. There is no up-down force on the upper ball joint, other than the slight resistance from the rubber bushings. It just locates the top of the spindle in a horizontal plane. I suggest you just hold it together temporary (C-clamp or such) and drive it to any small muffler or weld shop, and they might charge $20 to tack it. Maybe a member here near you will help. If you really want a new UCA and can wait, I have at least one for an early-A, but don't recall which side. We go to UCSD every year or two for our son.

There are disk brake kits that work with your 9" drum spindles. I recall Scarebird has an affordable one.

Check for parts in the PST kit. I recall some kits are missing critical parts like the idler arm, which costs ~$40 for your car (Autozone, rockauto).