Of course, 'staking' a valve, that is, tapping it to seat it, does work. But, you should be careful to know exactly why, which is why i brought up the issue of dry/fouled guide, or valve seat interface carbon.
Yes, normally, if an engine has not been run for quite a while, it isn't wrong to run the
oil pump with a drill and see pressure for a few moments, perhaps less than a minute. But, if you will forgive me, the careful removal and replacement of the distributor opens up another can of worms, given your current skill and degree of precision, that you might not want to introduce this into the mix of currently uncontrolled variables.
Alternatively, a simple spray/dribble of
oil on the valve stems & guides might suffice for these purposes. Either way, don't ignore certaining that the #6 ex valve is free and clear in the guide, and that it closes with ease. Don't force it too much if you find serious resistance, because you may score the stem (not likely) or seriously score the guide (more likely, since it is softer) and then it must be replaced for sure.
i'm gonna' wish it was a momentary glitch, so as to not require the head removal again. But, valve guide issues are potentially very serious indeed, so my wishfulness isn't in any way related to the reality of your valve guide/stem/valve/valve seat condition.
i've unfortunately seen aviation wrenches 'stake' valves with impunity and request a sign-off without a notation in the log about how the compression was achieved and on which valve. This MIGHT be reasonable on a 'self-maintained' low compression 65hp Piper Cub, which is rather easy to park somewhere if it fails. It is likely a necessary option on a radial-engined fighter with the Japanese hitting the field and we need to get up in the air, NOW. But, it is certainly NOT acceptable in a 350hp turbocharged twin-engined cabin-class altitude cruiser with 8 seats and big baggage used regularly between here and the Bahamas. Or on your precious Cobra engine, unless your budget has provision for learning by experiment.
If it sticks open too much, too deep, you are going to be buying at least one piston, valve and gasket set. Maybe lots more. Think about it. What little bit could possibly prevent your spring(s) from closing that valve? You DO recall how difficult they were to compress, right?
It is typically the hot exhaust valve/guide that sticks, not the MUCH cooler intake components, just as it is the ex valve that burns, erodes, over-heats, warps, etc. It took years of practical experience to learn just how to keep ex valves working, just how long was the minimum on the seat to cool, how to rotate, how to dampen, how to harden, etc... Exhaust valve operation is very tricky technology that looks disarmingly simple as we just buy the parts and install.
You get the idea...