Yes those are Umbrella seal on those heads.
The air fitting will work. Putting the cyl your working on at TDC will save your Compressor as you look for whatever tool you just set down somewhere...
You may or may not have to machine the valve guides OD to fit the Positive Seals. Depends on the measurements. You will have to pull the heads and remove the valves to use the guide cutter.
While I'm really not against Positive Seals, since they lube the valve stem and guide from the top gap
the seal top gap is critical. Too small you burn up the guides and valve stems, too large and you have a smoker.
Working on KISS principle going back with Umbrella seals (possibly a better material than you currently have) is not a bad way to go.
https://www.enginebuildermag.com/199...s-and-designs/