What broadhead for low poundage hunting set up?

[FallAirFever]

I am hoping to get my son up to 40lbs draw weight before this hunting season. I'd like to get him on a deer with his bow. What broadhead would you recommend for him. I am thinking a fixed blade cut on contact like a Montec?

Set-up is Diamond Infinity Edge, 24" DL and growing, right now he is just using Beman Jr arrows but I plan on getting him some better fit arrows for hunting.

Thanks for your help!