Thermoquad rebuild.

That was rumblefish that talked about adding the ported vacuum inlet. I've never done one. I've always just hunted for a TQ that already had it. They're plentiful. Not hard to find at all. They have a small brass tube sticking out of the plastic body on the passenger's side front of the carburetor. It was actually used for the EGR, but it's ported vacuum and that's what the distributor advance needs so it's perfect for that. Most all the parts will interchange. You can change the main body and base plate out if you want to go that far.

For your mild 360 the 800 will be fine, but if you have or find an 850 first, run it.