Grear vendors

I had the same problems with mine but not the difficulty, as I worked out the bugs on a 4-post drive-on hoist.
and So, I cranked the trans up into the tunnel and pounded on the GV to make marks on the tunnel, then took the trans down, to pound on the impressions. Thus my dimples were in the exact right place. After a few tries the GV ended up pressed as high as it could go, and I moved on to the Crossmember, which, like yours, wouldn't fit. But mine was only a quarter inch or so short, I simply slotted out the holes. I had a poly spool mount up there, so I slotted it a bit too.
As to the Electronics , I think I used them for like a couple of days. Man that thing shifted slow! After I bypassed the module, it shifted like lightning, and so I started using it as a splitter. Shazzam that car got fast!
But, be advised, I was already using the A833od box, so now I had 7 useable ratios. including Double overdrive!
It didn't take me long to install 4.30s, lol.
Over time, and with other circumstances, I came to the conclusion that 7 gears was easily two ratios too many for the street. So I got me a CommandO gearset and plugged that in. The CommandO is the same as the standard 2.66 box except it has the 3.09 low.
With 3.55s back in, this becomes a super nice system.
Most of the time I drive it as 5 speed, but shifting into over after third gear. This gives me a short fourth and a deeper Fifth. (.715)
but when I am hotdogging, I split between first and Second, and again after second.
This gives me 4 very-tight ratios with just one pull on the stick, and she tops out 103 mph in second over, at 6800! Then into 4th it goes at 3550
Here are the Commando ratios in black and the GV in red, followed by how I use them.

3.09-2.41-1.92-1.50-1.40-1.09-1.00-.78
3.09-1.92-1.40-1.09-.78, normal driving (.715 od from 1.09)
3.09-2.41-1.92-1.50, splits of .78-.80-.78, hotdogging
The starter gear is 3.55 x3.09= 10.97, which is about same as 10.97/2.66= 4.12s with the standard box.
The 10.97 starter lets me run parades at 550rpm=4mph
I've had the GV now for about 20 years

Btw, it upshifts faster than I can pull the stick, but when downshifting, it inshifts a little later than when I push the button. So, I have to give it a couple of milliseconds before clutching it for a downshift, and then it outshifts by the time the clutch is back. It just takes getting used to. Oh, BTW, the GV manual says I'm not supposed to downshift into it, on account of this action can break it, instantly. I found that to be true.
Once the GV is all-in, I can't hurt it with my 400hp 367.

My opinion is that of all the combos I have tried, which is about every one, this combo is darn near as perfect as it gets, for the street. and for 400hp in the Eighth. My car goes 93 with it, at 6160, on a cam the peaks about 5500/5600. This ends in 1.50 ratio. @1.40 ratio, this drops the Rs to 5760.. One time I accidentally shifted from Second over to third, before the traps, and by the time I glanced at the tach, it's like WTH just happened, cuz the Rs were already back in the zone. It was like the Rs never dropped! But this was in fact, a 400 rpm drop, right about at the Power peak. Shazzam!

I highly recommend it, lol

PS, if you're gonna powershift the GV like I do,
get yourself a clutch-disc with a hub and springs that can take this kind of abuse, cuz my engine eats 340 discs and spits out the springs. One of mine cracked most of the hub out, one fine afternoon, lol. But I limped it home. This............ on the street, with 295s; Cooper Cobras IIRC, but mightabin BFGs, I can't be sure.
I changed my driving style., just a lil.