First off you have me very puzzled about the listed specs of only 1 1/2 HP and 6 CFM for each compressor unit, are you sure about that?
I am certain those three cylinder pumps are capable of a lot more than that even if they are single stage, however if the 1 1/2 HP rating is correct then the CFM sounds about right. For sure an extra 250 gallon tank would be major overkill here and while that much storage would indeed add a usable amount of run time if that 12 (total) CFM rating is correct then it will not add as much as you might think and you will still find yourself running out of air, the recharge time for 330 gallons of storage with only 12 CFM input would be a real pain to work with. 12 CFM is just not enough to run a decent size body shop no matter how much storage you might have because the extra run time is still going to be a trade-off and the larger the tank the bigger the problem. Those huge tanks you mention are for very large usage rates such as you might find in a multiple employee shop or factory setting and they must be mated to a compressor(s) of a rating that closely approximates the normal demand, this is to prevent unreasonable cycle rates that would occur with a huge demand and a relatively small tank capacity. Tank capacity needs to be sized according to CFM input and demand and unbalancing this pump/tank ratio, either too big or too small, will create problems.
Is this going to be a multi-employe shop? How big is your CFM demand anticipated to be? If you will be exceeding your compressor capacity by more than 10% on a regular basis then you need a larger compressor and a larger tank mated to one that is too small will only compound the problem. If the extremely long recharge time is not going to be a problem, although I would think that it would be in a body shop, then that much storage would work to supply cooler and drier air but the extended run times could be very hard on the pumps and motors. If your primary concern is cooler drier air then there are better means to do this and IMO you would be much better off with the 80 gallon tank you have if indeed you have only 12 CFM.
We need a little more info here since this is apparently to power a large shop. What is the AMP/Voltage ratings on those motors? How much peak CFM demand do you anticipate?
I notice you said "two stage motor" ? Were you instead referring to the pumps? Those actually are single stage pumps pictured there, is that a picture of the actual compressor you intend to use?