That boat is complete junk, recalled, and you need to send it out here so I can dispose of it properly per Hazmat regulations........

Seriously, good find! Been in the market for a good one (For what I'm gonna do to the poor thing) for some time. What pump is in it? Beleive it or not, I've seen them with Panthers, Jacuzzi's and even one with a Drake. Sleek was nowhere near brand loyal when it came to rigging boats. Berk/Dominator/American Turbine/Aggressor is what you want for that hull! It WILL rock!
Don't really matter much what engine you put in there. Glad it's a Ford, but other than that, sounds like going from scratch. Original engine mounts on the SST were a little weird in that they bolted through the hull on tops on the tunnels. Big holes, weird pedestal mounts, not needed. Those holes I would carefully 'glass back in and use a rail kit (many sell them on here, JBP, Cyclone, etc) bolted through the stringers, and yes there are stringers glassed into the insides of the tunnels clear to the front of the boat, and mount your motor of choice off that using motor plates for whatever engine you're installing. Be aware of driveline angles, etc, many threads on that here.
That being said, the quagmire with the SST is that even though its already 20' long, it LOVES a set back pump. If you're looking for total performance, or, god forbid it has a Jacuzzi and you're changing anyway, it responds well to setbacks. A lot of 'glass work doing it, however, and it seems to respond best to a set back that puts the "hand hole" cleanout cover directly in the middle of the transom, rendering it useless.
Good luck, and get some pics up!!
Ray