I drove mine for months with a valve going bad. It won't hurt anything really other than your mileage and power. Normally the valve just burns and it doesn't hurt the seat or anything else on the head. So I would get on teamswift and get a set of stainless exhaust valves if you plan on keeping the car a long time when it goes bad. Just pull the head and seat the valve like any other valve and reinstall it.
Since it is gutless check the cam timing it might have jumped a notch. If the timing is set properly and the distributor isn't more or less centered in the adjustment holes it might be off a notch. The cam belts are cheap and pretty easy to change on these things. If you didn't jumper that one wire in the underhood diagnostic plug like it says on the sticker then you have the timing way off though
With that compression on a cold engine then there is really nothing wrong mechanically with the engine I say and it is probably just something out of adjustment or needing a good tune up. Off the top of my head here is the stuff I can think of to check
Distributor cap and rotor for corroded contacts
fuel filter
plugs and wires
ground strap
ignition timing
cam timing
I am sure I am missing stuff so hopefully someone will help fill in the list.