Struck gold with the bad SE logic board--it's got a Dove 030 accelerator installed. Too bad it needs re-capped! For now the SE is up and running with the other board.

Also, upon closer inspection, that drive bracket from the beater SE can be used to mount a third drive. Although it was not used as such in the computer I pulled it from, it apparently can sit on top of the upper floppy drive. The hard drive is mounted on the bracket's rear.