Update regarding my search for a master cylinder:
Even though I haven't even finished checking the heavy duty/offshore JK master listed above, I may have found another option:
99-2004 Dodge Ram 2500/3500 MC's appear to have the same bolt pattern, same thread size for the brake line attachment ports, and have a 1.25" bore! Have to check on the height of the reservoir to see if it hits the hood, and the push rod length.
I love having options. This one, if feasible, should give considerably more flow than even the upgraded Teraflex (aka OEM BR6 heavy duty brake option master cylinder) unit.