Nice project... I know early units had weak piston con rod issues. Mine failed and I used a Tx (73') crank assembly. Can't make out your taillight but we'll assume it has the Yamaha dirt bike unit. Yours has fork gathers... they were dropped during the production run. If you do an engine top end .. pistons etc etc... this is the model year the requires breaking the cam chain.... the gravity the chain runs in between the cylinders has a web connection. Mike's Xs sells re-pop stock mufflers. I'd go proper restoration... do not bobber.. cafe'.. I help out at a small shop dealing with early Xs units... restorations.... and have done a few of the Xs1's..... parts are get'n difficult to find. (marks650yamahas)... You have an excellent base for restoration.