Regs for drift state nothing about it, but hillclimbs is the point of the build and sports sedans have no rules, 4l engine car needs to weigh 1100kg, thats about all the rules, can be a space tube frame.
lloyd smiths build is a good read, didnt want to copy his build hense the irs, manual convo is sorted, CRS bell housing, custom flywheel and custom clutch. looking at an autronic ECU