Its from the CB750KZ, FA and FB models from around 1980
It's been on the shelf for about 20 odd years so has some surface rust on the conrods and in the little end area. I would say its a good crank that might need a conrod or two ish depending when cleaned up. Just in case theres pits in the little end area, Hence the price.
Have a good look at the pictures for the overall condition
If you would like more pics or info please email me.