Yes, but, it is trickier than just a manual. Kinda tricky by the 40 booster and firewall with a lever-type spring compression tool (home-brew compresses the spring farther which is important). It is plenty covered in this forum. Don't loose your valve keepers down any holes in the head, stuff...
Valve stem seals have nothing to do with pressure from the combustion chamber. That pressure is held by the valves themselves. Valve seats (on the head), is that what you mean?
The very high compression is a good sign. The vacuum is a good sign. I wouldn't rule-out a vacuum leak as the source of heat (lean fuel, not leaking valves or rings). However, these things are designed to oil the valve stems by having some pass past the seals, and if they are original, they...
I'd bet that more than half of a chance that it has nothing to do with the carb, but the valve stem seals are leaking. It not only makes the intake port kinda restricted, it fouls the plugs quick. Hence the hard cold start, and the can't-stop-it-when-hot - glowing plugs or valve surfaces is...
Had trouble with solenoid stuff in the past.
Don't underestimate the inexpensive Chinese carb. Everyone makes such a big deal about carbs, but, it is not much more sophisticated than having a home with a working toilet - is it clean, or does it leak? Aside from the whole, who messed with the...