Thanks, guys! I won't lie to you - I'm thinking of replacing the old SunTour derailleurs with a new Shimano set - front and rear derailleurs and 7-speed freewheel hub - paired to a handlebar-mounted shifter and brake set up. If that's what I end up with, that little heart will come in handy as an anchor point for cable stops.
Also appreciate the advice on paint . . . and that's exactly what I'll do . . . have the frame painted at a local shop, then maybe dress it up by taping off the frame and painting the lugs an accent color. Somewhere in there - after the color coat and before the clear coat - I'll have to fetch the frame back to apply the new NISHIKI decals . . . unless the paint shop is willing to do that for me.
Thanks again. . . . Duane