Howdy,
I love to catch Chum on the N.F. also, just remember that targeting them is technically illegal there. When fishing "Fly Fishing Only" water 12lb. test is as heavy a leader tippet that may be used. That being said, I fish for Steelhead and incidentally hook a lot of Chums using a heavy purple fly on a 4-5ft. 12lb. leader with a strike indicator on the fly-line. This set-up dead-drifted will result in far fewer foul-hooked fish. One more thought, when a fish is foul-hooked just grab the line and break it off in order to prevent a long no-win struggle. Without the ability to turn a Chum its stupid to try to get them in without over-tiring the fish.