When you say CR seat, do you mean an actual Factory CR750 replica seat? The CR750 seats were extremely short so you would also want a CR750 style tank that was long and slender. I doubt either would mount at the stock K locations...
OR do you just mean Cafe' Racer style "Bum Stop" seat ?
Airtech makes a Cafe' style seat specifically for your bike.
http://www.airtech-streamlining.com vintage seats
CB75021
Honda CB750 SOHC 1969-77 Cafe seat
Overall length: 28"
Seat pan lenght: 18"
Width front: 8.5"
Widest point: 10.5"
Please note: only fits Honda CB750 SOHC hinge pattern.
This cool cafe bubble seat was developed especially for the CB 750 K chassis to work with the stock seat latches and seat lock. It has two options to mount the seat lock (to match the different positions on early and late models). You can flip the seat up just like your stock seat to get acces to the battery, tools etc. This is as close to a bolt-on operation as it gets!
Works with the stock tank.
Add the upholstery pan below for a cushy seat and you're ready to roll.
Now if by some chance you DO mean a factory CR750 race replica, they have those bits too, even the beautiful long lean tank!
http://www.airtech-streamlining.com CR750 1969-77 I only know this because they have a similar kit for my 450 and I have drooled over it for more than a year.
81 Honda CB750C - Current Project
67 BSA Spitfire MkIII - Next Up (Full Resto)
81 Honda GL1100 - Bob / Cafe´
80 Suzuki GS750L - Bratstyle
72 Honda CB450K5 - Basket Case
73 Honda CB350F Cafe' (Gone but not forgotten)
Don't wait for opportunity to knock... kick the door down and drag the old harlot in!