externally balanced torque converter with internally balanced engine

alright so I have a 70 340 that is internally balanced. I'm working on an engine swap and I find out my new torque converter won't work because it is for a 904 non-lockup and I need a lockup torque converter which I can't find at all. let alone with the correct stall speed 10 inch pattern I need.
my question is, is there anyway I can use an externally balanced torque converter with an internally balanced engine. the old torque converter that came with the transmission that actually fits is externally balanced. is it as simple as getting the weights off of the torque converter?