When shopping for my current boat, a deal-breaker was good access around both engines. OK, so I compromised a bit on access to the outboard side of each, but basically I can see and work on any part of either engine or transmission. IMHO an engine in a box with access from the top only is asking for trouble. The boat harbor950 found looks to be in fine condition, but eventually something will go wrong and it is very hard to fix what you can't see.
If all else fails, read the instructions
If it ain't broke, don't fix it