'75 360...any good?

The only problem with using the original torque converter with a b&m flexplate is your converter was made for a 273 which had a smaller pilot hub (1.55" vs. 1.81") so the 273 converter used behind that 360 will probably break something because it has no front support. You really need to change the converter to the larger pilot hub to mate to the engine. Also keep in mind your trans. is the older one (assuming it's original to the car) so the spline count is 18 where-as the newer 904's are 27 so make sure and get the right converter.

Come to think of it I'm not sure anybody makes that combination. A 1.81" pilot hub with a 18 spline. If you can't find one you'll probably have to have a machine shop make a spacer.