A sealed enclosure of .98 cubic feet would give you a Q of .7 and a F3 of 89hz with a linear taper from -6dB@ 67hz down.
Reducing sealed enclosure to a minimum of 0.6 cubic feet keeps you approximately linear above 110hz and gives you an F3 in the mid 90s. Smaller than that enclosure size would not be advised, Q is already in the high 80's here.
If you choose to go with a vented enclosure, 2.0 cubic feet with a 50hz port tuning frequency keeps you very linear down to 60hz and keeps phase coherent (identical to "sealed" phase) down to well below 80hz. F3 is right at 50hz and at 40hz (low E on a four string bass) you're at -9dB. Not bad. If you do two, 3" diameter vents 4.95" deep with at least a 1/16" radius roundover at each end, you'll be in good shape.