what type/make of contacor would i use?
also i would only be using this for short durations like 30 seconds
lastly if i switch between forward and revese would i need any type of delay?
... Type of solenoid or contactor would require some additional research ... would probably depend on your project budget ...
One additional concern would be the instantaneous full power condition that would be generated by activating the motors. There is a rotating propeller effect called cavitation, which occurs when you exceed certain conditions ... kind of like spinning your tires, except with a propeller in the water.
It might be a good idea to devise some sort of partial or stepped speed control. Maybe several coils of heavy copper wire would create an inductance, that would retard the maximum current buildup for a short period of time.
... Again ... calls for a little experimentation, if you can afford it.
... Regarding the previous idea for using parallel wiring of the motors through the H-Bridge ... I concede that it would work. However you would double the current magnitude flowing through the solenoids ... over 100 amps. I suggest that a conservative design ... with a longer life ... would use two separate H bridges, one for each motor.
If I was going to build this, I would find a well stocked auto salvage yard, and get a set of 8 identical auto starter solenoids. Then construct a working circuit that will actually get your motors turning. At this point, you can determine if you need to worry about a delay, or stepped control ... or whatever else. ... Proof of concept would be a big step forward.