Recommend you set your goals first bro. How much power are you looking for? What other mods have you done or plan to do?
V2 STi motors came with TD05H out of Japan. Much more kick than the TD04, and I've seen 230kw ATW on that set up (with all the other supporting mods of course). Should bolt straight on and they're pretty bulletproof - and pretty cheap to pick up. Are you still running on the V2 grey injectors though because if so, they may have to go as well. You may be looking at another tune as well for the G4, but you will need to ask a pro on that one!
The angled V2 top mount is why you'll see that most of the old school STi's have front mounts, although it's a matter of choice. The flow ain't great on those top mounts but again, it comes down to your goals.