alvin's rite, the 4G63 evo or VR4 is a much better choice. have had a couple of frens using the eterna tt engine, one of them whack RM10k worth of extra mods but in the end not much difference from the stock 6A12TT - SERIOUS SHIT!
personally i'd opt for the evo if i could afford it, evo3 is 'n' would b the popular choice to plonk in but expensiv!! but it features (according to what others have told me) ported head, lighter internals and other bits here n there etc etc... i used to use this engin (in proton body also), very responsive even in stock condition but i threw it away cos block owez got fuct up cos it's weak! last time young n stupid (well still quite stupid la) dunno sh.t so owez fork out money 2 repair repair repair!! didn't mod anything just got SAFC stock evo3 and bigger turbo, redline it every nite after a months plus problem after problem finally blow hahaha!
evo3 pretty high comp so if u do go for the evo3 n wanna boost the sh.t out of it then metal gasket n work (strengthen) the block!