The bolts, when installed, are very close to the back of the block. They require a "thin" head. Some aftermarket bolts may not be thin enough.
If you have the proper bolts they shouldn't contact the back of the block, but will untill they are tight or near tight.
I usually start one and run it in untill it bottoms, the back it out1/4 to 1/2 turn and repeat this procedure untill all four are in, then do a final tighten on them all.
It is possible that if the bolts are too long they are bottoming in the holes and sit proud even though they appear to be tight. If they are proud, once again, they can contact the back of the block and restrict engine rotation.