How can I test this out?

74 Charger. I pulled the entire dash frame and all it's subassemblies out of the car. Painted the dash frame, put on new dash pad, changed from standard cluster to rallye, sent out all gauges to be repaired. I found a complete 74 harness that was in great shape and did ohms check on the whole assembly. Changed all the lamps to LED (where they would fit) and checked these with a 9 volt battery. It is now all back together and I'm ready to install the whole assembly. I would like to put some power to everything now before I install it in the car to make sure it all works and no smoke so that I can repair it before install. But I am not sure where to go from here and how many volts/amps to check it with? Anyone else ever do this? Could use some help. Thanks

Easy, use a car battery or jump box....ground the dash frame at one of the mounting holes, put the positive side of the battery to the heavy Guage black wire from the bulk head connector.... that will power the entire dash harness

As well, you will need to connect an ignition switch, or jump the ignition switch Molex accordingly, to verify any key-on functions.

Ok, I was more than likely over thinking this. Just didn't want to burn anything up. Thanks

feeding the black wire at bulkhead OR straight to the amm stud on black side as mentioned will automatically feed the ign switch plug at red wire

sure will need to be sure ammeter black wire at least is installed on ammeter and safe from any accidental ground touch around.

If ign switch is unplugged it will need then to jump red and black wires on ign switch plug to feed ACC side of the fuse box OOOOOOR... jump out the male auxiliary terminals embossed at fuse box, just right down the fuse lines in front of fuse box to feed both sides of fuse box ( from BATT to ACC ) with just the black wire at ammeter or bulkhead being sourced.

NOTHING TO WORRY ABOUT high loads if you will just test some stuff around like bulbs, gauges. Be sure cluster/dash frame is also propperly grounded. This will keep safe gauges, which are feeded from Voltage limiter and it NEEDS to get a GOOD ground to not burn gauges.

Standard cluster gets gauges/VL feeded from run circuit ( blue on ign switch), but Rallye Cluster gets sourced from ACC circuit ( black on ign switch ).

When feeding blue circuit ( if you do ) at ign switch plug you COULD get seatbelt light and buzzer working. You can ground off the brown wire with yellow trace at bulkhead ( or at a provision available around ) to turn those off. I don't recall if they could actually work still with seat/seatbelt sensors harness unplugged thought

Once everything is conected ( including the ACC side of the fuse box ) you can also ground the violet and gray wires at bulkhead plug of engine harness to check for temp and oil sender gauges function.... and blue wire on driver side kick panel plug to rear tail light harness to check for fuel gauge function....

This will test gauges AND related wires on dash harness. Sure you can check those straight to the gauge studs too

Lights will be able to be tested from switch itself. Switch is linked to the batt circuit ( black wire of bulkhead/ammeter )