> I need to put it on its feet for a few weeks, then return it to
> its dolly to finish up the work underneath, then again onto its feet
> after completion.

You can do it like we do at Piano World.  This method was taken from the
Steinway movers from the factory.  I have altered the technique for use
with your player stack which too often gets creamed during a tip over by
regular movers (usually doofus-es).  It sounds like your grand board has
casters on it.  I would suggest you use a J-bar or other lever to tip
each end of the piano up enough to put 4-2x4 or 2-4x4 blocks under it
(approx. 4 in at each end) to get the whole piano about 5+ inches off the
ground and with no casters able to roll.

Hopefully there is a pad between the piano and the grand board.  scoot
the piano keybed to the middle of the board width so that it cannot slide
off and hit the floor.  Put the top and tail legs on the piano and screw
on well.  Put the pedal lyre on and screw down with the lyre braces, if
possible.  Now use a moving pad (quilt) and fold it up until it is about
4-5 inches thick.  Lay it on the floor so that the pedal lyre will sit on
it when the piano is flipped.  Turn the casters up, but if your Mason is
the art deco with the box on the bottom of the leg, then it won't matter.

Now roll the piano over toward you onto the two legs and lyre.  The part
of the piano where the third leg goes will be up so that you can easily
fit it in place.  When you screw the leg on it and the caster will be up
in the air.  Now sit on the bench in front of the piano keyboard with
your knees under the treble end of the piano.  Use your tippy-toes to
lift the corner of the piano off the pad under the lyre enough to pull
the pad out from underneath.  Voila, the piano is down.  Reverse this
procedure to put the piano back up on its side.  Having spent most of
my 30 years restoring unassisted, this technique has been a godsend.

I hope to never get the back problems that my other reproducer restorer
friends now have.  This will also work with some minor second person
assistance here and there, but no one gets any major weight to deal with.
The thing to watch for is the stack touching the floor.  (Usually not
possible with lyre in position.) You may elevate the tail end of the
grand board more to solve this.

The other thing to watch for is the broken drawer syndrome.  Make sure
the drawer is fixed or wedged in the slightly open position so that it
will not glide open or closed at the wrong time.  This would either smash
your fingers or worse, break the piece out of the bass end bottom of the
fine wood drawer front.  I often put this finished front on only after
the piano is finished and tested out.  This way there is no possibility
of breakage or scratching.

Good luck,

D. L. Bullock Piano World  St. Louis