Billman,
Wouldn't the use of the subaru gearbox give you 5 speeds in reverse, since you turn them around and install it in the back end of a bug? (some people do have that problem with 901 boxes that get 'repaired' by s/one that thinks its a 914 box also, LOL, sorry Jake)
Ricola/Rich has a subaru engine mated to a 915 trans, which makes more sense to me. He has a site (look at the links section, I believe it is
www.ricola.co.uk) that is very informative. As you can also learn from his site, he uses a Kennedy Engineered Products flywheel to adapt the trans with the 915 gearbox.
Why do you want to use the subaru or a Toyota gearbox? The latter I don't understand even more.
Walter