Race datsun A-series cylinder head assembly, port matched sidedraft inlet manifold, sidedraft carbs package.head has had a lot of work done to it including:
Skimmed surface to raise compression
Heavily raised porting
Ported oil galleries for better flow
Very large valves (40mm in 33mm ex),
Double valve springs
New valve stem seals
Rocker springs have been replaced with shims

Sidedraft inlet manfold has been port matched to head. Sidedraft Mikuni carbs with newly fitted needles and seats from USA. Were run on race A15 (1608cc) previously. Come with shiney trumpets. does anyone know if this size porting will work on a 1200, my last build a number of years ago, was with a GX head with 37mm/29mm and not as much porting, this porting is huge.

Will it work on a 1200? Sure, if it is a racing 1200 and you are running very high RPM.

Sounds like you're considering buying Chris Cain's (AKA Cheater 5) race head.
That head is a pretty serious piece of kit. It wouldn't be real flash on a street motor, especially if you were running a cam that yielded low manifold vacuum.
It would be bad as on a forced induction motor. If I win the lotto, I'd buy it in a snap.

how much power does it have?

power? as its just a head id say it has none
its not just a head that makes power you need the rest of the engine too.

ha

i thought it was on an engine