Test fit the cam now to make sure the cam bearings are ok... Sometimes the bores can be slightly small when the bearings are put in, so it's best to catch it now while the block is bare than to catch it after you install the pistons...
Just install the cam and make sure it rotates.... Then remove the cam to build the block up...
Sometimes the ID of the bearings crushes in a bit when the cam bearings are installed in their bores... Make sure yours are ok...