you cant remove the pv, it is bolted in from the bottom of the cylinder.
this is why you need to take top end off

Taking it out maybe not so bad.... Turning the Zilla over so I wouldn't drop it putting it back in would suck! 

D$allstar I think was the poster. Sounded like it was possible.... But what do I know

i think its possible, but never tried.  but you might be able to get a wrench in there to loosen the screw then unscrew it with your fingers.  but i don't know.  won't hurt to try.

i've made a couple block off's for the pv before. 

Not the easiest thing in the world to do, but I've done it.  So I know it can be done.   

I faced the exact same dilemma: Just got a new top end together and was getting a leak at the pvalve.  I DID NOT want to have to disassemble that puppy just to get an o-ring in there.  So I took a stubby 10mm wrench (I think it was 10mm) and got it loosened.  You only get like 20-30-degrees of motion, so you have to be patient and expect it to take a while.  Once I got it loose and got the linkage and water pump idler out of the way, I could get my monster phillips screwdriver on there at an angle to back it out.  Isn't that long of a bolt.

Maybe an open-end wrench socket attachment on a 1/4" drive would work better?  Maybe find a cheapy wrench and grind it down to fit better?

Is it me or is the power valve bolt that holds it in the cylinder in a blind hole in the cases when the cylinder is sitting on the cases?

Yeah it's buried in there. Even with the side case removed, getting to that bolt isn't easy. Normal open end won't get in there, the casting in the center case prevents using a socket wrench from inside the clutch cover... Cyl had to come off.