This is what it says in the wiki.

What types of 5-speeds are available?

56 series trans
small, light as in original B110 4-speed with visible ribs along case. The 5-speed versions were 1:1 fifth-gear "direct [trans]mission" (non-overdrive)
60 series trans
smooth-case medium-size trans as in B310. These come in 60L (dogleg) and 60A (non-dogleg) varieties
63 series trans
large trans commonly used with L-series engines, a version was also fitted to A-series engines in B210s. The 5-speed version is a "dogleg" shifter. It was fitted to 5-speed hatchbacks from 1976-1/2 through 1978 model years, and starting in 1977 for Canada

Finding one will be the hardest thing, as they are getting a bit thin on the ground.

Next option would be to do a Toyota box conversion, contact Dellow in Sydney they should be able to set you up with all the bits you wil need.