My only comment is that you might have an easier time replacing using the actual replacement. Even at that by the time you get into the icebox to use existing holes it can be difficult leaning into, while your holding onto, and working upside down. I replaced mine 10 years ago and it was not fun. I guess if you have a lot of frozen food to store the larger makes sense.

We replaced our original Adler Barbour several years ago and considered going with a larger "freezer box". After considering how difficult it would be to mount it, I decided to go with the original size. It was easy to mount using the original mounting holes. Basically, a " plug and play."

I replaced mine 15 years ago, quite a job contorting myself to get it installed.  As our boats are of a different generations.  Check the vertical & horizontal clearance of  the unit before ordering any thing larger.  Space around the unit is necessary to provide the cooling effect.

I've got a compressor I had listed on the classifieds.  It's new and in the box.   I attempted to install it with a new evaporator and the capillary line was plugged.  I'll sell it to you for half price of a new one. If it doesn't work, you'll need to ship it back to me at your own cost. You might want to give it a shot if you are thinking about replacing your unit.