Check the crank before you do anything. That will help you decide what the next steps are if the crank is good, may consider the conversion on the cam plate / cams or go gear drive or need to have the crank fixed and go from there.
Tensioners are the big getcha / gotcha
I would also do a leak down and compression test to be sure all else is right with the engine.
As far as motor work:
Consideratons will be
Throttlebody, exhaust, cam and compression. There are enough builds on the site you should have no issue deciding what works for your style of riding.
A Recommendation would be
10 to 1
Gear Drive cams
S&S 570 ez start no screwing around with compression releases and having to clean them or degunk them.
48-50mm throttlebody
Stock injectors 4.35
good 2 into 1 pipe / falsie if you want that symetrical look
Deck your heads .040- .060 depending on how many CC's they are
Flat top piston
Clean the heads up
Ride it for 50-100k
CVOStu and a few others have this combo on this site and its tried / true and runs well.