Well I see the fork part, I never clicked the image before. As for the pipes and stuff, paris never said what his plans for the bike where. If a person was looking to have a factory look, then sure pipes and stuff would be an issue. But if he likes the bike the way it is, then the minor parts dont mean much. For me, I like a bike that looks how I want it too look. My 78k has a vetter fairing with a tall backrest. Not factory but i like it that way. It would be worth 800 to me but maybe not someone else. A seat is easy to come by for this year and side covers are available also. The wheel is no big deal except for cosmetic reasons. So really, if the bike runs good and is in sound mechanical shape and Paris likes how it looks or plans to make very little changes to it, $800 might not be bad.
For me I would not pay 800 but then I would not want anything but my 78K unless it was VERY cheap, stock or not. All personal pref really. Thats why I say mechanically sound.
Well, Paris has the bike and now he gets to decide what he wants to do with it.
What I'm getting at about the pipes is that no matter which route you take with the bike, having a set of factory pipes for an early K bike that are in good or better condition is extra gravy. I agree, I want my bikes to look the way I want them to. Some have the factory look while others have been modded a bit (my Ducati Monster bears just a little resemblance to the way it did when it rolled off the assembly line) because I like both looks. But you can't poopoo the idea of taking into consideration the condition of the exhaust and whether or not it's original when looking at possibly purchasing the bike, no matter what your plans are for it.
Yes, the seat and sidecovers are available for the early Ks but you will pay for the condition of such parts.
For me, depending on which model K bike it is and it's condition, I would pay $800 (I might even pay more depending on what it is). In fact, I just bought my K1 at Mid-Ohio and did pay $800 for it. And, it has a stuck motor. But, it is completely intact, has a set of HM300 pipes that are in very good condition and the frame and engine numbers are correct. It is a prime candidate for a total restoration (which it will get over the next few years). My K2 I bought almost 3 years ago for $500 and it's now worth more but it's still a sub $1k 750 due to cosmetics and the lack of some original parts (plus it's turning into a cafe bike). My K5 I paid $950 for about 2 1/2 years ago and it's worth well over that because of the work I've done to it which now includes a set of solid HM341's (replaced the #3).
Keep in mind that the days of the sub $1k SOHC CB750 are drawing to a close. While these bikes have enjoyed cult status for a number of years they are now being recognized for the true classics that they are and prices are starting to reflect this. So, if you are unwilling to pay $800 now for a 750 that will need work but is in reasonable condition with a good exhaust, in a few years if you change your mind, you will be unable to do so. Unless you find some unsuspecting owner that just wants the old clunker out of his garage (which will continue to happen albeit on a less frequent basis). A little food for thought.