IMO:
Stick with the 4cylinders, and stick with Toyota..... I suggest a 4age of some sort....
Going from a standard 4k to a standard 4age is a whole different ball game in its own....
I have a mate with a 300hp atw ke55 corolla, 4agze w/ TD04 turbo.
I also had another mate with a standard 4agze in his ke70, with a FMIC, and it was crazy......
There is a lot of work in shoehorning in an atmo sr20 or ca18 not to mention a turbo version. And as for a 1ggte or 1ggze? :jamie:
Go for the 4agze, find a decent ae71 for front end parts, swap 'em over, bolt it in, and wire it all up.....
The difference in torque will surprise you......!
Or just spend the money on a hypo 4k / 5k....... get that BRAP BRAP going.....
:D