[Cajundaddy]

Alright, gentle suggestions from a guy with exactly one mini-split install in Oceanside CA:

Because of the vintage nature of your home which is quite elegant, I agree with hiding the outdoor compressor units as best you can. Sticking on the siding like a barnacle is sure to disappoint so give this some thought.

Also, due to the ceiling height and custom moulding this install screams for ceiling registers. If I hung a wall register across the moulding my wife would give birth to a live baby cow for all to see. I think the mini's can work here and will transform your comfort levels but you need to make them disappear as much as possible. It is a clash of cultures that should be addressed. The wall registers can be hung lower like below a window as long as there is good airflow but I would still greatly favor ceiling registers for a completely clean look. I assume you have a boiler and radiators for heat which is period correct. Ceiling registers would blend into the room great.

This might be a really good project for a pro with years of experience making modern mini-splits disappear into a vintage home environment. A very different job requiring finesse compared with adding a mini to a garage or workshop.