1975 B1 platform engine/gearbox options

[funktopus]

Hi to all. I have a 1975 VW Passat which runs on the same B1 platform / chassis as the early Audi 80's of that time. I'm thinking about an engine and gearbox swap as the 1300 cc and 4 speed is a bit under powered especially on motorways. I'm fairly sure my choice of motors will be large as most VW / Audi blocks were the same but has anyone seen or heard of any conversions done especially on the gearbox side of things, i'm thinking late 80's early 90's Audi 80 or something ? Any help on this would be much appreciated.