Volvo M41 are a great option- 4-speed with a fifth gear overdrive. Cheap(can be found for around $300), and pretty much a drop in install (a shorter driveshaft is needed). My recommendation!

T5 and T9s are what other people are using. More the T5s, but I think you need to mod the tranny tunnel to get the T5 to fit a 122. Either need an adapter plates to mount the transmission to the bellhousing, mods to the driveshaft, mod to the tranny mount, shifter mods (try John Parker's website for more info -> v-performance.com).

There is a company is Australia that makes an adapter for Toyota five speeds too: http://www.dellowauto.com.au/main.html

Paul