That looks beautiful Steve, well done! The Z1 was probably the sexiest looking bike built in the 1970's, I can't think of any other bike that so stirred the emotions of young men at the time. (and some old men now)
I'm shocked though, to discover that you've been harboring fugly K7's and K8's on your property, but I guess you're like old Mother Teresa, looking after those poor Lepers in India.
K7's and K8's were truly the SOHC4 Lepers, so maybe like Mother Teresa, one day you'll be awarded the Nobel Peace Prize for your humanitarian work? Better you than me mate, I just don't have the stomach for it, just looking at one makes me want to puke! 
Oh Terry Terry Terry. Not sure if you remember, but the K7 has the same basic motor as the earlier models?!
And with an aftermarket exhaust, can sound rather good (I have an RC in the Batcave waiting).
Maybe you should buy one again and give it a shot!
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Ha ha, what's that old Texas saying Steve, "fool me once, shame on me, er, no wait, fool me twice, shame on, er, well, what I was trying to say, is, er, well, you can put lipstick on a pig, but it's still a pig?"
The K7/K8 was a kneejerk reaction from Honda, they actually stopped production of the "K" model because they thought that the "F" was going to be the natural evolution of the mighty CB750, but when sales fell through the floor (I bought a brand spanking new 1975 F0 in March 1978 for a heavy discount because they had lots of them in crates they couldn't sell three years on) they brought the "750K" out of retirement to fill the gap until the (horrible) first model DOHC 750's came along.
I have to agree that the engine is a gem, (probably the best of all the CB750's) it was just a wolf in pig's clothing.
BTW, your K4 looks lovely mate, keep that original color, that bike is a survivor, and will only ever be original once. If I owned it, I'd fit some new OEM pipes from Yamiya and be happy. Cheers, Terry.
