bellhousing bolt size

I'm fitting a set of new rear motor plates for a Funnycar. The existing one has 3/8" bolt holes, the new plates are cut for 7/16" How common is the 3/8" bolt setup?

 

On a hemi the block has 7/16 inserts but brad sells a step stud for the block that makes it a 7/16 to 3/8

 

Thanks, we got 3/8" drilled plates from RJ / quartermax and step studs from Wizards.