This is my current ride, a 1980 FLT that has been refitted with a 1988 drivetrain.
I bought her almost like she sits and have done a little maintence but few modifications.
She runs well at highway speeds and the only problems I have had other than the 'Y' pipe breaking have been due to rigging and poor wrenching by the last owner (broken bolts in the tranny cover, etc).

The rear 'Y' pipe broke so I had my brother weld it and braze up the holes.  It screwed the chrome but I have put 2500 miles on it with no problems, I can live with the way it looks.

This is the timing cover I had Doug Dulmage burn for me.
Check my links page for his web site, he is really good at doing this stuff