truck engine/trany needs thrust bearing

I have a 47 ft motorsailer. I have a ford f-250 with 6.9 l diesel and manual tran. I plan to put engine and trans in boat. Engine rated 175hp@3800rpm. I will use about 80 hp@2200rpm. Keel cooling, dry exhaust, heavy duty marine alternator. standard shaft/prop installation. Reason, old mercedes engine, ie expensive hard to get parts.$500 water pump! $40 for ford. PYI has thrust bearings,to expensive. Bearing suppliers have dual acting thrust bearings,just like PYI uses $2-300. I need good ideas on simple ways to mount bearing between flange on end of prop shaft and transmission.
I understand a marine engine/tran is a better solution. This way will cost about $1500. I have all materials on hand except bearing and shaft. Boat is steel so mounting bearing securely is not a problem.

 

You can rebuild the Mercedes for $1500. Are you sure it is worth your effort to install an engine that is not designed for the application?