Finding the correct gph for diy sump

Hey everyone,
On a recent post, I read that a sump pump rating should be greater than or equal to four times your tank cycle. For example, my 33 gallon tank would be 33 X 4 = 132gph pump or greater. I have 150 gph pump that I want for a sump but I also need an overflow to match. Can someone give a suggestion as to where I can find an overflow box with this low of a rating. Thank you for your help.
 
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