Yeah possibly, just there are quite a few things about sr's that i don't like.
I'm sure they could be tuned to be quite responsive but this isnt a common focus when tuning them a lot of the time. Another thing to keep in mind is do you honestly need 270rwkw? I'm thinking not. there is that sr hachi and I think its a near stock motor with a fmic and ecu or something along those lines and that's incredibly fast. How much power dose beau have?
I agree the potential for endless power as even in Australia I have seen them reach 1000hp (some gay blue drag monster s15).
I think that it wouldn't be half as bad if you recessed the motor into the fire wall a few inchs, you would probaly have a better balance than factory.
You will be pushing shit up a hill to get the weight down to 900kg, with the motor box and hilux or equally heavy diff..
I think your being sensible with learning how to steer it with a 4ag to start with. Learn to really steer and not just use your right foot because you have dose.