All the components are well suited to your lathe project. I'd warrant most suggestions (one immeasurable benefit of posting on HMT.net, besides we don't charge $.00!) might be;
1. The Crouch base is a great foundation. Put 4 isolation/ leveling pads at the very corners [or extended somewhat lowering center of gravity] vs the C-channel, motor, and drive train. Base looks tapered, might become unstable at speed.
2. Add a pillow block with longer shaft outboard the Craftsman headstock. That will generate better balance and rigidity at speed, and room for a jackshaft for a greatly expanded RPM range. Will allow lowering the motor for weight advantage, adjustment, and conventional length belts.
3. 'We' will want to see what the spindle end accommodates in chucks, faceplates, and drive spurs. If there aren't any threads, the Shopsmith's use a .625 (5/8") diameter and setscrew flat - easily duplicated. In reality, threaded spindles are do-able too, but will take a little engineering; once again, duplicate a commercial design for desired tooling.
4. The only dimensional challenge I see has two facets. That will be centerlines of tailstock and headstock coincide in two axis, especially in heights above the bed. Parallel [in reference to the bed length] can be 'swiveled' at the headstock or shimmed at the tailstock. One will influence method chosen to get the heights registered.
5. Building your own allows planning additional features, to incorporate at convenient intervals.