Honda-SOHC

Hi Guys

I'm undergoing a full restore on a UK 1975 CB750K2 that I've bought last year and having fully rebuilt the forks, discovered (when fitting the chrome fork tops) that the bike seems to fitted with CB500 Four forks! (the CB500 has a threaded rod running from bottom fork leg that screws into the top fork tube nut - after researching CMSL schematics online) Anyway, I've bought a set of early K2 forks to rebuild and as the fork tubes are beyond repair and am looking to buy a new set - probably pattern as i'm going into shock at the amount of money I'm throwing at this project (can't do things by half unfortunataly!). I've seem a set in America on ebay that would work out at about £160 a pair plus import duty.
But I've also seen a set for £92.90 post free for 76 - 78 F. (http://www.ebay.co.uk/itm/Pattern-Front-Fork-Stanchions-to-fit-Honda-CB-750-F-SOHC-76-78-/271172968636?pt=UK_Motorcycle_Parts&hash=item3f232b20bc) - Anybody know if I can use them with the K2 fork bottoms?
I've put a few pics on of rebuild so far for interest
Thanks
Phil

Hi Guys
Its my first post and so hope I've done it right! I'm rebuilding a K2 that I bought as a basket case - engine in bits and cases really badly corroded and bits missing. So I decided to buy a complete engine from D&K that was on ebay. But as I had a friend who has a contact at D&K, I got it via him a bit cheaper than advertised on ebay. When it was listed on ebay, they stated engine number that I checked to be a 72 K2. (never made a note of numbers)
Anyway, I have stripped it down completely for rebuild and there is no engine number stamped on the cast rectange on the top engine case. The casting has not been ground and still shows the original 'speckled' casting (on the rectangle that the number is normally stamped on).
Is the number located somewhere else?
How does this affect V5?
I didn't get any paperwork, although my mate is seeing if he can get it retrospectively.
Any help would be appreciated.
Thanks
Phil