Hello Erick,
The minimum height of a reconditioned cyl head is 84.00 mm (page 119 Technical Data Booklet 1972). It is not in specs if your measurement are correct. It may be usable but can cause a lot of issues with compression, valve adjustments, valve clearances, cam shaft alignment etc, in other words a risk at best.
Double check you measurements. Measure at the ends and center of the head. Make sure your measuring tool is accurate and you are using it correctly.
I never have my heads cut unless absolutly necessary. There is just not much to spare before you have a boat anchor on your hands.