Help on my 1964 4 speed swap

Have no idea about the relative strength of the two types of joints, but my understanding is that Chrysler used the (more expensive to produce) ball and trunnion setup for years because theoretically it should be smoother than a regular u-joint, because (again, if I understand it at all), the B&T joint is basically a constant velocity joint, whereas the cross shaft u-joint speeds up and slows down as it rotates. In practice, I've never been able to tell any difference in smoothness, and the cross-shaft type u-joint is definitely easier and cheaper to service.