Before you get started, you may want to give thoughtful consideration to what kind of restore you're interested in performing. If you want everything perfect for a particular year, God bless, but you'll find it more difficult/expensive to get there. Your rewards at the time of sale will be greater if you do a restore "dead nuts on" or what I'd call a "true restoration".. but I'm in denial about ever selling my mistress. I've chosen a path I'd call "period correct". Get "period correct" parts which might not be the exact year but it would take a discerning eye to understand that your directional stalks should be coming out of the headlight bolt instead of the fork ear. "Period correct" (in my tiny little mind) requires correct colors, factory seat, factory pipes... You get the idea. A good example of what I'd like to do is paint a headlight bucket and fork ears to make a K1 using K1-K6 parts for most everything else. In your case, you're starting out with a K1 which is an excellent year but it's not too hard to convert it to a K0... at least in looks. Get a K0 oil tank, side covers, air box (to heck with the expensive carbs!) and some paint. In terms of exhaust, you may make your decision between HM300 and HM341 based on how you ride. They have different costs, different longevity, make different noise and make differing torque at different places on your tachometer.
That's only two categories. There are a few other categories but I don't think you fit in them. There's "fully custom" which is folks that want to do they're own thing... (cafe, bobber, chopper, heavily modified etc.). Then there's folks ("cobblers") that are just happy to be on an SOHC4 and will cobble together a K7 front end on a K4 with a king and queen seat and not worry about Terry laughing half way 'round the world about "the motorcycle with a toilet seat".
Be warned: If you choose to go "true restoration", me and the rest of the "period correct" guys (weenie wanna be's) will swarm and be examining your starter button, saddle type (there are many), fender mounts, the numbers (or lack thereof) on your pipes, etc., etc., etc. (I've never quoted Yul Brynner before
). Again, if everything is "year correct" and in excellent condition, these bikes can go for 20K or more.
Welcome to the madness. This is a great place. I've made lots of friends here. I guarantee you'll enjoy the ride.
John