Hi Pat,  I bought myself a butane micro-torch at my nearest Home Depot
for under $25.00.  It came with several tips.  I use the one that works
like a propane torch (only much smaller, of course).

I run the flame around the inside of the metal upper valve seat until
I see the shellac bubbling, but only just a little bit.  Then, I use
a small pair of needle nose pliers to pull out the valve seat.  If the
valve seat does not come out very easily, I put a bit more flame on it.

I have removed an entire set of upper valve seats in under an hour this
way.  This method has worked for me and might be worth considering.

Regards,
Rob Buckingham
Penn, Pennsylvania