2 3/8" Glass hole saw for 1.5" bulkhead.

I don't have one but I've done it before and would be willing to help out...

 

Yeah I don't have that size myself, but rest assured, they're easy to do. Just make a plumbers putty dam and fill it with water and take it at a moderate speed. Then when you start punching through and all your water starts to drain have a big cup of water ready to keep pouring in the dam until you get all the way through. No sweat, seriously I've done dozens of them....and with old bits too!

 

also....check the mfg specs on it and make sure it's not tempered!!!!

 

Me too.  I don't have that size.  I have the size for the 3/4" ABS, 1" ABS and a 3" which works for the 1 1/2" Banjo brand bulkheads from Theisens (those suckers are *really* heavy duty!!).  That's what I used on my sump..but due to size considerations, you probably want to go with ABS on your display tank.
What are you using for your overflow box?  You may want to just buy an entire kit that comes with the hole saw from Glass Holes.  Here's their kit that would be the correct size for your tank I think... http://www.glass-holes.com/1500-gph-complete-kit-gh1500kit.htm
--AJ