YOUNG GUN: Putting Nitrous on 318!!!

So you only took 2 degrees out, 12 to 10? And yes the total number and your base go hand in hand at this point. So you went from 34 to 32 total, not near enough of a beginning safety margin IMO. If you want more initial you need to reduce the mechanical advance in your distributor to keep the 12 you started with and back it down to 28 which is a good starting point for total on nitrous. I'd live with the idle now and concentrate on taking enough timing out, then tailor it once you get the tune up figured out.

Please stop before this turns into a nitrous blew up my engine thread.

You really need to take enough timing out first and get the fuel jetting side done. Contrary to popular internet belief, a fat tune up is worse than a lean one with nitrous. A fat tune up will continue to run and break stuff, lean usually quits running. Get that sorted out, then worry about dialing timing back in. Once you have that figured out the distributor can be worked over.

I don't know how versed you are at running nitrous, but, learn to read plugs REALLY well as they will tell you a bunch. If the electrode strap is getting burned off that's usually too much total timing, so pay attention to that.