71# 14.5"x40" too small?

[abosely]

Hey guys sorry to ask such a noobe question. But over here on Big Island the larger propane tanks are difficult to find, but I did pick up some 71# 14.5"x40" and some 25.7# 11"x18" & 30.4# 11"x24" tanks.

Would the 71# tank work for the cooking chamber and use either the 25.7# or 30.4# tank for the fire box?
I can get the standard 20# BBQ tank for fire box if the 25.7# or 30.4# tanks would be to big for the 71# CC.

I would like a 16" - 18" CC if I can get one, but since I have these would like to use them if big enough to function.

Would use reverse flow if it would work on such a small CC or traditional side fire box & tuning plates if better for the small CC.

Actually it would be nice to have a small smoker in addition to a larger one when can find one.

Cheers, Allen