Hi Tim,
Jack's right. You'll need to angle them down considerably and this can be tricky with the 632-LR due to it's weight and lack of threaded inserts on the back. You can use the BT77 mount, but to ensure that they don't slide forward over time, a security screw needs to be drilled into the underside of the speaker. It's a small screw so with the cherry finish, this isn't a huge deal. It's all but impossible with the black lacquer finish.
Given the improved performance of the 5b, I think that it may make a better candidate. It still doesn't put out quite as much bass as the 632-LR, but it's considerably more fortuitous than the 532-Lr in the bass department and the midrange response is very comparable to the 632-LR. I think that blending these with a sub would yield terrific results.
Caleb Denison
Home Theater Guru
Aperionaudio.com