just to update people. After I upgraded from a 6.x base to 7.1.
I needed to add back in the various graphic tool kits such as ffmpeg, ImageMagick, etc.
other than that, there shouldn't be anything else to do.
all database entries survived properly as it related to Gallery2.
The only hicup I had was with file UIDs which got messed up. In particular www's UID got changed around. In my case I simply used chown to set the UID back to www for the g2data directory.
I have filed a bug report in bugzilla on this issue as accounts and passwd seem out of synch.
report is
http://bugs.contribs.org/show_bug.cgi?id=2219