Chris,
Nice work on the restoration
15 pages was a fair amount of stuff to read
I have a 1A tiller I use on my 125 ( and 122 ). I purchased deeper V pulleys for the mule drive from NAPA, part number 7-05212 ( you need two ) and also the long drive belt from the PTO to the angle. I have an early 125 and it was belt AX-144 ( shorter belt iirc ). I also purchased the tiller belt but forgot to get that belt number, I'll add it later. The NAPA belts work great and have a big cost savings.
tiller belt 3VX530
These units are really heavy duty. Right after I got mine, my next door wanted to put a garden in. I cut right thru the sod and by the second pass was down at full depth.
My wife saw how well that worked and I ended up "sculpting" down a dirt mound that was here when we purchased the property in '03. I flipped up the back shield and just backed the tiller right in. It worked great.
Started with this
and when finished
Here's the set up on my 125 ( fluid filled 10.50's on the back -- I had the 8.50 ags and 62 lb gilson weights on the 122 with the blade )
The 125 & 1A "chewing" away
Jeff