Firstly, its "I see said the blind CARPENTER, as he picked up his hammer and SAW"!
Secondly, forget the cam change until you find the true culprit. It's still a lot of work, and you don't know if it will do you any good at this point.
Thirdly, if your"base" timing is 30deg btdc, I don't think it would start/idle. If by "base" you mean "static" or "initial" timing, it should be somewhere around 16-18 deg btdc(I'll have to ck my manual to be sure) That, plus advance (mechanical, vacumn, or comb of both) of approx 20 deg = max advanced timing of 36-38deg. Do you have readable timing marks on your damper? If so, mark your initial and max marks with a contrasting paint.
Install timing light,start eng, let warm up and stabilize to correct idle speed. Your timing light should now show the "initial" timing mark under the pointer. If you have specs on your dist, it should tell you at what rpm max advance occurs, I would guess around 4000rpm. Run the engine to that speed and hold it there. Your max advance mark should now be under the timing mark. Increase rpm slowly and see if the max timing comes off the mark, it should not.
BUT.... as with all things, when you are trying to isolate a problem, you MUST start from a KNOWN point. In this case it is the timing marks must be verified before anything else !
You must find true TDC, and compare that with the marks on the damper & pointer. Do you or someone you know, know how to find true TDC???
Once that is done, you can check cam and ignition timing.
IF all the above does not produce the desired improvements, THEN the next step is to go into the engine, and since you don't know for sure whats in there, if it were mine, I would tear it down completely, and start from scratch!
Let me know about the TDC thing. Maybe you can get whoever helped you with the leak-down test to give you a hand with the TDC and timing checks.
Good Luck,
Ted R.
