So many questions
First contact an RTA engineer to get a comprehensive list of HIS requirements - they vary from engineer to engineer although they all use the same set of rules.
You will need a chassis strengthening kit (CRS in Vic can supply)
You will need dual circuit disc brakes capable of passing a brake test.
Other stuff like retractable seat belts, demister & brake fail light etc may or may not be required.
UC column and rack can be sourced from swap meets, ebay or from other forum members - you just need to start looking and putting "wanted" ads out there. Shortened Commo racks are also commonly used with HR front ends - either behind or infront of the crossmember.
Ken