There are ALOT of parts out there for the XS,from frames to remanufactured engines,to turn key custom bikes that are all new.
Check out, mikes xs parts,ardcore choppers,gs motor company,tcbros,etc.
There are a bunch of them being built on another site I am on.
www.bobbertalk.com check it out a bunch of good guys over there.
I don't klnow about the Honda 650,but the 750 has alot of stuff available.Check out
www.hondachopper.com they can tell you more about it.
There is a guy(Tigman)on here,and a couple other sites that will hardtail a Savage frame.