Fighting a bad cold so have to stay away from the machinery as I'm fond of my fingers.
Doing more research on this.
Found an excellent source of parts.
Trying to verify the rumor that the Supra is basically the same diff for a cheaper LSD.
So far aftermarket gear sets have been lower than stock but I'm not done looking.
Did get a nice PDF exploded view this morning if I only knew how to post it.
EDIT: Looks like 3.07 may be the tallest gear available.
Need to look at my tires OD too.
EDIT 2: Seems the tallest
available reverse cut R&P is 3.73
7.5" Supra diff is supposed to fit.
Looking at 26.57" Dia. tires on 15" rims for the rear.
If I can find the right calculator I may be able to see how much that helps.
The 4Runner setup has been used to create a narrow IRS center section for V6 and V8 use.
Since my car will be very light I am going to look at some other reverse cut R&P sets, Suzuki, Dana 30?
I may just have to make my own housing.
Hmm, if I'm going that far maybe add reverse too.
Would like to find a good Saab 900 free-wheel device to use in my reverse mechanism.
Going to try to finish repair of my CNC indexer, then I will be able to cut my own splines.
If I'm rambling blame the flu.

One more edit, then to bed.
Seems I may be better off to use a Dana-30 reverse cut R&P, 3.07 is readily available.
May be able to modify a housing, or just make one.
Aluminum Jeep 30A IFS is a disappointment as the right ratio is not available.
Since the car will be a little heavier than a bike I think 3.07 may be just fine and I really am not looking for 165 MPH in this car.
It sits so low it makes a standard 7 look like a lifted vehicle, but the Aero in not much better.
At least I am into the Toyo diff's dirt cheap so I can certainly get my money back.
May still make an IRS center from them by modifying for two short axles as posted at the top.