I would advise against the gel batteries, honestly. If you get a nice AGM you will have no problems for 5+ years. AGMs have a nice CCA that our 'big' v-twin needs.
The fact that it wasn't charging when hot could mean the R/R (if you did not relocate it, then this can occur), or even stator. You may want to perform all the resistance tests in the electrical sticky. Also as suggested go over all your connections, reseat them, etc.
1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Rebuilt Forks w/ Progressive Springs
VN750.com Grill Cover
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R
1990 Kawasaki Vulcan 750
1998 Honda VFR800 FI
2014 Honda VFR800F
1989 Pontiac Firebird Formula 350