Ok,
All is well in Twin Reverb Land. I dunno what I did, but the new fuse didn't blow. My best guess is that the tube was not fully seated into the bias tool, and/or the bias tool was not fully seated into the tube socket, and then something happened to blow the fuse.
Anyway, I'm now biased at 30 - 31 mA. The four tubes are waaay closer than the four "matched" Boogie Tubes, and the Matched PI tube makes a dramatic difference. This is probably partly true because the existing PI tube was not matched. I'm sure there are PI tubes out there that happen to be matched more by accident than design. My existing PI tube must've been on the mis-match side of the coin.
The low number GT 6L6R tubes, (they are #3 on the GT 1 -10 scale) are the best sounding tubes I've put in the amp, and they distort at a loud, but livable volume.
It's like I have a brand new amp. And at the cost of tubes, I cold've bought one. :-)