A project in the true tradition of Zilch!
(Seriously, has anyone else taken more old-school speaker boxes, put modern parts in them, and designed a real crossover for the new parts in the old box?)
What I'd do is build a new baffle to fit flush with the step, and screw-mounted so you can get underneath it. I'd mount the SEOS12 flush to the new baffle. For the woofer, I'd rout the inside
of the new baffle out to fit the woofer's mounting ring. Mount the woofer to the sub-baffle inside, and on the front side of the new baffle gently round over from the woofer suspension out. (The cutout for the woofer on the new baffle will look kind-of like a flattened urn: a step on the inside, with a round over on the other side. That way, you'll hide the basket frame and better align the driver motors.
Originally Posted by beastaudio
I tried to look up the specs on the TD12s
Unless already you have a pair, you should think about using an actually available mid woofer.