hey welcome to the wonderful world of supras :)
ive seen people do 1ggte,1jzgte,2jzgte,uzfe conversions before but the most common would prob have to be the 1jzgte (2.5 liter twinturbo six)
if i were you i prob wouldnt go with the 1ggte and just get a turbo 7mgte or turbo charge your 7mge...