So after so much speculation as to what could possibly be wrong with my bike (condenser? points? coils?), it turns out that the battery was shot and wouldn't hold a charge. Mike over at Hiway Cycle was nice enough to fill up my new battery with acid and charge it up... and first kick she roared back to life!
Apparently, the ignition on the R5 relies completely on the battery for spark. So, a bad battery = poor spark. A good, fully charged battery should be able to run the bike for a few hours or so, with no lights on.
Anyways, looking forward to a nice long riding season.