Changing gear ratio options in MKII rear differential

[RatLabGuy]

Hi guys.
I know this seems odd, I'm actually coming from an off-road truck background. Explanations later.

I'm trying to find out if there are any ring/pinion gear change options for the 87-92 Supra/Cressia 8" rear differemtials. I understand non-turbo is 4.10 or 4.30 stock.
What I'd really like is 4.88. 4.56 or 5.29 could be dealt with but not as ideal.

Soooo... either,
1 - are there R/P shops that sell alternate gears for this model 8" differntial, or
2 - anybody know if the R/P sets for the 8" Toy trucks are a replacement match? Those have may options and are widely available from 4.10-5.79.