Start by spraying every nut,bolt,mount etc. with PB blaster or liquid wrench. It won't hurt a thing to start soaking the rust. Where in the southeast do you live? If you live near the Jacksonville Florida area I have lots of shops I can recommend. I restored a 1997 205 and had to unbolt the mounts on the side of stringers to get the engine out. The bolts that hold the mounts to the stringers were stainless and I was able to break them free without a lot of force. You could also unbolt the mounts at the engine block and transmission interface if the bolts are not too badly rusted. I was able to restore my mounts to workable condition by soaking them in an oil bath then using lots of elbow grease and a drill with wire brush. If you replace them or rework the mounts be sure to take measurements so you can set the new or reworked mounts back to the same settings so the engine alignment will be much easier.
*I see you are from the Tampa area.
There are lots of prostar resto threads here is one with some links and pointers. http://www.mastercraft.com/teamtalk/...t=52998&page=2