initial setup of alternator

[Henry's HenryJs]

I am also doing an alternator setup on the 4cyl, here are some mock up pic's.

[HJ-ETEX]

Where is this "Also" coming from? I seem to have missed any previous warnings.
You are using an early GM alternator with a separate regulator. There is nothing wrong with using that for mock up purposes because the external dimensions are mostly the same as a 10SI. Really, you should use a 10SI (internal regulator).
I find it interesting that your alternator has a double pulley. Only a few GM applications had double pulleys. I had 1 alternator with such a pulley and needed 2 more pulleys and I had to work the parts catalogs.
However, you are about to screw up. The HJ & Jeep 4 cyl engines use wide belts. Sure you can put a narrow belt in the wide pulleys on the water pump and crank, but you are going to find that the narrow belt wears out very fast. You need to use the original wide belt.
What you need is a a wide belt pulley for the GM alternator you are going to use.  And it is not that hard to get one if you have some clues. A lot of Model As have GM alternators installed. Model A vendors offer wide belt pulleys. Where do these vendors get these pulleys? Well, if you know a REAL automotive electrical rebuilder, he can find you a wide pulley from the same source.
And finally if you are feeling cheap, try removing the pulley from the HJ generator and putting it on the GM alternator.  I put a 10SI on my Jeep CJ3A and used the pulley off the CJ3A generator. I put a 10SI on a Ford 8N tractor and used the pulley off the tractor generator.

[Henry's HenryJs]

ETEX, the "also" is referring to my post on the distributor. I also have a stash of alternators and just grabbed that one for a mock up of the pieces. I am aware of the belt issue and will be seeking a pulley, probably the one off of the gen, or look into one of the ones you mention. Henry

[Fid]

Just a side note, my '52 Henry J had a Hudson generator on it when I got it.  The voltage reg was shot when I got the car and it wasn't until I looked at the generator, and even though it said "Hudson" on it it was clearly an Autolite unit.  The Autolite number was one digit off from the one used on the Henry J (Z vers A or something like that) and the only discernable difference was the Hudson unit had a much smaller diameter pulley on it, hence it would spin much faster and that's what burned up the regulator. I found a correct generator and regulator for it and installed them over a decade ago and they work fine.   Speed (RPM) matters on a generator whereas it doesn't so much on an alternator.

[HJ-ETEX]

Well, you weren't thinking of it in this way, but the pulley diameter can make a difference on alternators. The replacement internal regulators for GM alternators require 1000 rpms to kick in. Once the regulator turns on  the rpms can be reduced and the alternator will continue to charge. I learned this when I put a 10SI on a Ford 8N tractor. You started the tractor, pulled the throttle 3/4 open, the ammeter jumped to charge, and then the throttle could be cut back. The initial guess was there was something wacky about the regulator but this was a NAPA regulator and the parts catalog had the disclaimer about the 1000 rpm. On a modern car, you may or may not even encounter this problem since 1000 rpm is slightly more than a fast idle. But on a tractor that tops out at about 1800 rpm and the pulley diameter ratio is around 1.5:1, you notice it. A small flathead like a 134 would probably be much the same.
Well, I was using the pulley from the 8N generator and I didn't have the option of a smaller pulley. You can see though, that a smaller pulley on the alternator would cause the regulator to kick in at a lower engine rpm.
Now one solution would be to find a factory original internal regulator, but there is the problem with identification and if that unit went bad, then you are back to the original problem.