Roosies T4 fitted the 2wd trousers perfectly.
Don't lower the CR unless you need to, as it will increase lag on what will already be a laggy turbo, decently set up it won't need lowering.
The ones I've been in didn't do anything serious until about 4300, by which time a T34 car is a long way ahead, just depends what you want from the car.
Plenty of our Scandinavian buds running over 500 on group a HG and arp stud/nut kit without problem/
Your best bet imo is work out/decide how much power you want to end up with ?, then you will have a much better idea of the spec you need engine wise to make that power.
tabetha