Tuning and building ported box

[Fewstanator]

My box is going to be abou. 3ft x 2ft x 9" wih 3/4" walls, which comes to 3.36cu ft, i used a website and got a port size of 3x9x15" for 34hz. Im puttig in 2 12" kickers with 750.1 , im not sure if the box is quite big enough though as kicker says min box volume per sub is 1.75cu ft, should i just go sealed? is this a good tune for the box size and is the box even big enough? Thanks for any help