I just did this with a '69 GTS that had sat for about 20 years. I'm not saying this is what you should do, just what I did.

1) It was full of oil, I left it. My thought is that old oil with a lot of zinc is better than the new stuff without.
2) I agree with using compressed air to blow out around the plugs, it's amazing what deposits in there.
3) I pulled out all the plugs and hosed the cylinders down with Marvel Mystery Oil and a syphon gun. About $25 at NAPA.
4) Turned the motor over 4 times by hand with a breaker bar on the damper bolt. That checks the stuck valve potential.
5) I hosed the cylinders down again with MMO and spun it over with the starter. I used a GOOD battery so I got oil pressure quickly.
6) I gapped the points and reset the timing with a test lamp.
7) Filled the carb with gas through the bowl vents, put 5 gallons of premium in tank with a can of SeaFoam.
8) Put the plugs back in, squirted some gas in the carb, and rolled it over.

Started right up. It took about five times before it would stay running but once it did I ran it on the fast idle cam for about 20 minutes to get it good and warm. Pulled the plugs again and checked compression, all between 140 and 150 psig.

Again, I'm not saying that's how anybody should do it, just how I did.