Update on the block I have which came from my warehouse and this block we will call brand-X no name or paper work came with this block.
After measuring the mains which measured 2.6385 my centering rings are not going to work and the cam tunnel is 1.197 to 1.198 so my my adjustable fixture is not going to work in this block.
When I get time I will line hone the mains and make a plug for the cam tunnel.
I will get some pics and post later.