Thanks for the help guys, I've been looking into the wrx diff option for a while and it seems the way to go.

What do you reckon about fitting R31 front struts, brake assembly and rack and pinion steering to it? I can purchase all the parts for $350 aus. It seems to me to be a good base to begin on.

To start with it will be a mild 5.2 litre backed by a 4 speed, then when funds permit I'll fit the blower and stroke/bore the engine out to 6.4 litre and install a 5 or 6 speed. I'm aming for 450rwkw