I assume you measured the locations? If so, how did you measure - just curious? I got my B1 numbers from Scott Koffel. Your numbers vary just a little bit - I am not surprised they worked. I made the holes in my B1 spacer/adapter 0.0290" just to be on the safe side. They fit very well.

Jim - the 0.070" difference is very real. I am o-ringing a set of valve covers for a member here and he has the Indy EZ heads. The covers are unbranded cast aluminum valve covers. You can see the layout of the valve cover holes in this attachment. I tried these valve covers on my TF270 heads and NO WAY were they gonna fit. They didn't fit exactly per the numbers. I am making spacers for the TF270 heads and my trial spacer fit perfectly using the numbers TF gave me.

He also measured the EZ head bolt hole locations with calipers and you can see that it confirms the numbers Indy gave me.

When I have a chance I will measure a set of 906 heads.