904 Flex Plate for '72 340

I'm kinda in the same situation here. I have a mildly built 340 and 727 trans. So please tell me if I'm wrong but can you get a 340 balanced flex plate (the B&M one everybody is recommending) to replace the factory one and get a converter without the weights on it? I'm really heaving a hard time finding a converter balanced to a 340. I have a Hughes performance now that's pretty nice but I'm looking for a higher stall speed.