Uca access

I was an alignment guy for nearly six years. I see no advantage to the windows, on an A-body, at all.
But I got these tips for a streeter .
I see no advantage for tubular UCAs, and
If you use the OEM stuff, then use the Moog Problem Solvers, and
before you install the new eccentric cams, put some anti-sieze on the shanks, only the shanks, and make sure the cams are physically able to squeeze the whole she-bang together tight. The flats on the shanks of new bolts are not cut far enough up towards the heads and they could use a couple more threads cut on to them. I usually install hardened washers under the head to solve the short-flats issue and another under the nut to solve the lack of sufficient threads on the other end.
With Problem Solvers I can usually get about 5 to 5.5 degrees of caster at Zero camber. By the time I dial in .5 negative camber, the caster may be down to 3.5 to 4 degrees, which on a streeter is fine. Both sides are never the same, and I have to go with what I get on the shortest side. Yes, I put sandbags in the drivers seat to simulate the drivers weight; this is very important with softer OEM T-bars.
The above is true for 67 and later cars, IDK about First Gens.
As for adjustable UCAs in competition; yes you can get more caster with them.
But then you have to correct the bump-steer that all that caster causes. Plan on spending at least a half-day at the alignment shop, if you bring the custom parts that are required to make the changes. If the knuckles have to modded. it's gonna cost ya.
Even just 3.5degrees of caster is a PITA to correct for bumpsteer.
But,after correction, IMO, it is worth every hour/dollar