If you want units that fit the existing cutouts exactly, you may be pretty limited. Obviously you can make the cutouts bigger if needed to fit a larger stove or sink, but you can't make a square hole round, say, for a round sink.
What some people do is cut out the whole top of the galley (leaving a 1-2" lip all around) and attach a new countertop of whatever material floats your boat. (Better if it's
light enough to float, so granite is probably out.
) Then you can make whatever size and shape cutouts you need.
You'll need to look at clearances underneath (especially over the fridge/icebox) and compare to the specs of whatever you're installing. For example, you may not be able to fit a SMEV stove/sink combo unit over the
fridge. The location of the gas supply line will also have some bearing on what you can put where.
If your Boler doesn't already have it, I would incorporate some kind of support for the upper cabinet in your redesign. It not only supports the cabinet and its contents, but also stabilizes the shell to keep it from sagging.
What are you
painting? Just the Ensolite walls, or everything?