Your two AGMs will give you 310 amps total but for best battery life you only want to drain them 50% (about 12.1 volts) so you have 155 amps to use before recharging. You get the fun job of figuring out what you want to run, for how long, how many amps you'll need to run that stuff and how often you'll need to, or be able to recharge.
A deep cycle battery will only tolerate maybe 150 deep cycles (down to 20% charge or about 11.5 volts) while the same battery only discharged to 50% may be good for many times that many cycles.
What do you plan on doing with your bus? If you're plug in campground camping, you can bring high drain appliances (microwave, coffee maker, hair dryer) and use the heck out of them. If boondocking you use much less or bring a generator.