3x24 belt sander belt around two 3/4 plywd blocks approx. 3"x11"+ and a slab of something about 1/4" thick to drive in as a tensioner between the blocks is all I've ever needed to shoot this sort of end-grain joint. Start w/ 80-120grt. I don't think there's enuf difference between dowells or a plug tenon to be worth the worry which one. If you've got a Bridgeport, you've got all the mortising capability you need. I wouldn't even bother trying to index a handheld biscuit joiner for this ap.

jack