how much 20lb spectra would the calcutta be able to hold, assuming 20lb spectra is as thick as 6lb test. or should i go with the 30lb spectra? this will be for tossing bighammers in SW

Throw the saltwater baits on at least 50, 65 is good too- you don't need the capacity, but you'll have plenty anyway. You're fishing with the drag buckled down and you want to rip those fish out of the heavy stuff, and also cut through the kelp with the braid. I fish a CT250 with straight 65 lb. Powerpro and it works really good. Only thing you have to watch is too much pressure on your stick with the heavy line and tight drag. Don't do anything silly with the rod and you'll be in good shape.

one of the reasons i wanted to use 30lb is for the thin diameter. with less resistance i could cast farther and have it sink better on lighter jig heads.