How many ounces does 2 drams equal?

1 lb=16 oz, so 2 lb 2 oz = 16*2+2=34 oz

2 fl oz(US) = 4 tbs(US)

2 tsp = 0.333333 ounces

0.676280454 US fluid ounces

Gallons is a measure of volume, ounces of mass. Thus, the two are not compatible. You can convert for a specific substance, if you know the density of said substance.