I fashioned my own throttle cable using some generic parts from a Pepboys.
The radiator will probably have to be the stock E9 radiator. I used the E9 engine thermostat housing to get the hoses to line up. Plus, the later radiators all have plastic end tanks, which are quite bad.
The E9s like to overheat in stock trim anyway, so be prepared to upgrade to a 9 blade fan and viscous clutch, at the very least.