Perhaps headspace is not the correct term,I am looking for what the gap between the block and the barrel should be.

regards
N

The gap between the block and the barrel will be dependent on how far the barrel is screwed into the action. The headspace is a measurement between the breech face and a datum line on the cartridge.

post this question in the gunsmith section. very knowledgeable people there.

Just enough for a .005 feeler gauge to slide when the breech is closed but not more than .010" and without the h'space gauge.