I'd honestly just do some searching 95% of the info is out there. Read posts by BDI and Don, they are the two sources i got all of my info from. Both guys offer a ton of info from both ends of the spectrum.
BDI has a custom headstay mount for the engine that looks amazing, price was a lil rich for my blood, but would really have cleaned the looks up quite a bit, and for someone without any fab skills, would certainly be worth it.
My 250/500 hybrid is kinda different then anyone elses i've seen. Mine is a true hybrid "parts" bike, in the sense that I did not start with a full KX250. It would have been MUCH cheaper to just start with the full KX250...