think I got screwed on my new motor please advise!!!!

[cop-coupe]

I just bought a new short block from a engine builder I thought was reputable. It is a short block 306, my first problem was when I got the motor and unpacked it there were no holes for the lifter spider, so I had to drill and tap the holes. not a fun thing to do with an already assembled motor, but I got it done. Then I was getting ready to put my heads on and discovered the tops of the pistons are stamped with .060, I know this isn't a terrible thing but its not necessarily a good one either. I dont know that much about the internals and tolerances of shortblocks that is why I purchased a motor and dindt do it myself! Please give me your opinions on how you would handle this. and what the disadvantages are.