Josh--
The standpipe only quiets the overflow noise, it has no bearing on the issue of your tank overflowing. And neither does drilling, per se. As I indicated in my previous message, it sounds like your return pump is pushing more water into the display than can be drained via the overflow. Eventually, the display WILL overflow if this is the case. Spend a couple of bucks to install a value to dial back the return pump, or get a less powerful pump, or increase the size of your overflow drain. If the return pump is pushing less water into the display than CAN be drained continuously, your tank CANNOT overflow (unless something clogs the drain--but that's not particular to your situation, its a risk assumed by anyone with a sump). The dynamic of the loop is easy to visualize.
If you drill, and maintain the same return flow/drain flow ratio you have, the same thing is going to happen--your tank will overflow. If you do drill the tank, be sure to drill more holes than you have now, and/or ones of greater diameter. Finally, if you drill, you MUST remove all the livestock, water, etc., and have it professionally done with the proper tools. Otherwise, you're just looking to destroy your tank and kill everything in it.
This later option represents a serious amount of time, effort, and possibly a non-trivial amount of cash (depending on what's done) at this point. My advice is to save yourself the headache, and just dial back the pump to play with the flow over a few days. This is the root cause of the current problem, and drilling is not the most direct solution. Drill your next tank.
