71 engine bay wiring

Hi folks. Newbie here. recently picked a 71 number matching bb 4speed which has some fire damage in engine bay due to carb leak. Currently working to make it ready for body shop. heat pretty much destroyed all wiring under hood. I removed engine and tranny out of way to do some clean up and see what I can do before send it to body shop. Today, I removed the remainder of what used to be the headlight harness (connected behind the fuse box) and other part of it ends on the starter. I've been reading your posts regarding the ammeter and the fact that is not actually an "ammeter" but a voltmeter. There will some upgrades there (include electric fan(s), electric headlight and wiper door, 1 wire alternator etc) and I just don't see any point to get pricy original wiring for all 3 damaged circuits (about $700) and then cut and modify them! I want a real ammeter to actually reads amps passing trough it and have no problem to run heavy gauge wires to it. Anybody knows how to make some sort of original looking ammeter and make it reads how many amps you send to/receive from battery? Also, what should I do with oil pressure gauge? leave it the way it is and send the actual pressure to it or anybody convert it to a sending unit or something?? appreciated.

I would leave the oil pressure gauge as it is as that is more accurate than using a sender type. Also if it still has the plastic tubing running to it from the engine I would replace that with copper. The plastic will leak eventually if it hasn't already.