Hello Tony,
Now that we have the safe distances down, its time to get to work on the controller itself. If you want some real help, I would suggest opening up the box and taking pictures to post here. Otherwise we'll be mostly flailing around and not accomplishing much.
You never mentioned how many pads or banks of pads this thing controls. Good thing to know for a start considering the more pads that it controls, the more complex the internal wiring will be.
Did it have any kind of working continuity checking capabilities?
Several people have mentioned their commercial control systems. I could mention Wilson F/X Digital Control Systems which have been around since 1994. I know that's only 24 years, but I built my first launch system over 50 years ago and my first 8-pad system 48 years ago. I've built about a dozen low power analogue club systems for A thru G motors. And I've repaired and rebuilt several of them over the years. So I know a thing or two about what you're probably looking at when you open the box.
But like I said, pictures will help more than anything.
Just some things to think about:
1) all of the switches may/probably also need replacing
2) All the internal wiring probably needs replacing
3) all solder joints will need replacing
4) what condition is the enclosure in and what's the material from which its made?
a) rusty
b) cracked plastic
c) splintered wood
d) cardboard with holes
e) good condition?
f) steel, aluminum, plastic, fiberglass, ????????
5) are there any indicator lights, if yes, do they work? Can the burnt bulbs be replaced?
6) nostalgia is great, but is this thing worth the time and money you're going to put into it?
You might want to rethink the RCA jacks for igniter lead connections. They are inexpensive, but that's because they're not particularly robust. I wouldn't want to put this much work into something that's not going to last. I would suggest going with Anderson Power Pole connectors from Powerwerx: the pp15 in the paired red/black housing works great for the #16 AWG wire and are more than adequate for even 50 foot leads. And they have a panel mount designed for installing in a panel. Could make identifying igniter lead connections on the controller a lot easier. I get mine from Powerwerx and I use them for power connections and lead connections on some of my Wilson F/X components.
And you mentioned that you need an on/off key switch. Do you have one? If not, a rugged one is available from Digikey, part number CKC8039-ND
Also bulk alligator clips, 290-1942-ND for the 10 amp 2" long, barreled crimp on ones which work well with #16 AWG wire
There are also smaller alligator clips 314-1010-ND which are for up to 5 amps and about 1 inch long and work well with #18 AWG wire
Go to the digikey web site look up "test and measurement" products, then scroll down to test clips. Lots of different varieties and price ranges are available including solid copper! Bulk pricing available.
Look up the prices of the switches and everything else you'll need. Consider how much time this is going to take, then consider very carefully if this is a project that you really want to do.
If its a four to eight pad system, I'd probably go for it. If its larger? Well, things get expensive real quick.
I'm not here to discourage you, but I don't want you to start without considering the real probable costs that you're looking at.
Just some thoughts.
Let's see some pictures so that we all can be more helpful.
Brad, the "Rocket Rev.," Wilson