Stev-o , This was the semi chopper I built a few years ago that I grew out of, it needed to get back closer to stock. She's a good ride. Keeper? I have never sold a (SOHC) bike , aren't they all keepers?
Tews, 1st question, not so quick answer. It depends what is wrong with the engine. It takes me 2 days after I cleaned the outside of it, if I have all the parts, and the valves (takes me 5 hrs to do the head) , bearings, and pistons are perfect.... maybe 16 + hrs (or a whole Saturday) if I don't rebuild carbs , a few hrs more if I have to paint it.
Have done a motor over a weekend before but haven't had it running in 2 days because I usually paint the frame since the engine is out of the cradle. I don't buy pretty bikes and they are rebuilt painted, polished ,ready to ride in 2 or 3 weeks depending how late I stay up.
I find that I am always rushed for time, lately it is just easier to rebuild a 500 or 550 when I have the time and leave it on a shelf for the next project.
To clarify , Top end only ....for sure. Split the cases and paint...20 hrs. It would be in the realm of possibilities if the rest of the machine was good.It would be a long day.
2nd question answer: Between the 500's and 550's .......24, I had to do 5 of them a second time after Hurricane Irene.