the wiring diagram provided by haynes etc are pretty coomprehensive, if you are bringing it back to standard, they are the best! I would use the exsisting harness as a template. try speedsport (yamahatopdog) if you have money to buy a new one. try the xs650'sor RD 400 sites and you make be able to adapt one for the 400 (never tried it, but worth a try)mike's xs or HVC cycle
best machine possible? it depends on what you want from the bike, poser, commuter, show bike!