72 c20 5.3 swap electrical question

I have the motor in and engine harness hooked up, using 2000 ECM and stock fuse block. Question- what do I do with the 4 wires that were in the voltage regulator? I am using the alternator that came with the engine (and all accessories). So I assume the motor should all be fine as far as power but I need to get power to the chassis and interior, What have you done?

Eliminate the voltage regulator and put the 12v feed for the cab to one of the accesory post on the 5.3 fuse block.

Where do the 4 wires go to from the regulator?
Brown appears to go back into cab. Assuming red is from the alternator. blue and white must be small plug on alternator.