Try doing a search on "rail-kits", or "rail-Mounts". It's been covered pretty extensivly. It is possible to make your own engine mounting plates, but it would require that you suspend your engine in the engine bay, and start cutting cardboard to fit. From experience, it is a long drawn out process getting everything to fit. I'd say as close as we are to boating season (if financially possible for you) you would be ahead of the game to order a railkit system. I'm sure these are available from a variaty of places but the only one that I could point you to off the top of my head is www.hi-techperformance.com
If you decide to make your own, the only thing to be concerned about is to leave a bit of an angle (2-3 degrees) on your driveline. U-joints need to flex some to keep the needle bearings moving and not wearing flatspots on them.
Hope this helps..
Ken F