That should work fine. Just go through all the possible failure scenarios once you have your entire system planned out (i.e. pump fails, electricity goes off, overflow clogs or overflow box stops siphoning, etc...). I built my own wet/dry for a new 75 gal. I have had in operation for a few weeks now. If you need any info. on building a homemade wet/dry let me know (they are very easy and you can save a couple hundred $).
Good luck!