More or less. On the Pup, the wooden rails for mounting the engine are built into the tank area and the entire unit is designed to naturally sit with the proper thrust angles (the title of the thread). So mounting a 4-stroke only involves making some cuts here and there so that you can mount the engine a bit further back on the rails and adding some bits of wood around the edges.

The standard method for mounting a 4-stroke is to have it sitting on a "recessed firewall" which much easier to do than the term might imply. But on the Puppeteer you don't even have to do that because of the way the engine beams are attached to the tank walls.