I also feel like I can see too much of the gear when it's off, leading me to think it's not the correct manual starter. I don't have capability to attach files, but send me an email address and I can send the PDF with all of the part numbers and measurements from BCB (or anyone else who can post the file here). The BCB link to the file is dead now.
Edit
Found the post with the file attached:
https://classicbroncos.com/forums/threads/what-is-the-between-manual-vs-auto-starter.320321/
That PDF in the thread may have some gold in it to solve my problem
"
For the manual transmission starters the dimension from the back of the engine block to the aft edge of
the ring gear on the flywheel is .420 in, the starter ring is still .375, which leaves the forward edge of the
ring gear only .050 aft of the engine block. HOWEVER, this only applies to the old large diameter
(14 1/8” dia) 164 tooth flywheels! On the small diameter (13¼” dia) 157 tooth flywheels the backspacing
is the same as with auto trans flexplate. So, a starter for manual transmissions will not work with the 157
tooth manual transmission flywheel, even though it could be bolted to the engine.
The majority of the late model applications using the T-5 five speed transmission used the small 157
tooth flywheel, hence we see starters designated for a “5 speed manual trans”, it is not actually the
transmission, but the diameter of the flywheel (and subsequent ring gear backspacing) that dictates the
AUTO starter be used. It has nothing to do with a 3,4,5 or 10 speed trans, it is all about the flywheel that
they are using. If a customer is using the complete T-5 setup from some late model application (flywheel,
clutch, bellhousing, and trans) then they will need theAUTOstarter."
From the last 3 posts, I've got some measuring to do