Motor won't fire now...advice needed.

Weeeell I'm back, work has kept me busy. I pulled the RH head and exhaust. #8 intake valve was stuck open and bumped by the piston. Tim, my friend with the shop, was able to knock out the valve, clean out the guide, put in a new valve, and check compression. The head checked out OK. I found the heat riser valve(?) in the exhaust rusted shut and the cross overs plugged with carbon. I cut out the valve, cleaned out the carbon and did a re-assembly Friday night. At 12:10 a.m. Sat. morning I fired the motor.

Now a timing issue. I set it to factory specs last night and it was running smooth until i hooked the vacuum advance back-up. It gave the motor a 'lope' when idling. What gives? :scratch: