Existing hole in overflow needs to be drilled larger

I have dual overflows drilled for 1" bulkheads at 1 3/4". I have been having issues lately with some regular style bulkheads so after cleaning AC&C out of what they had, I went ahead and ordered some sch 80 bulk heads from BulkReef Supply. Didn't realize that in doing so, my hole needs to be 1 7/8. So....my question is....since I have never drilled glass - is it too much of a pita to drill a larger hole..(from 1 3/4 to 1 7/8) or should I return these for regular ones? Tank already has water in it but not full to where is goes down the overflows. Advice?

 

Thanks guys. Ended up sending the sch 80 ones back and ordered the ABS ones. Thanks for the reassurance. I do have another question - has anyone used the drain hose from basemen sumps for you drain hose on your aquariums?