With limited contractors and limited choices of mfgrs,I don't advise adding factors that further limit available options. Chose the best value equipment and hire a competent contractor to make it work for you.

A few things you might be unaware of. Heads at ceiling height work best for cooling while heards at floor level work best for heat. Heads can be mounted on inside walls by simply adding a condensate pump and occasionally backing up to a bath,laundry or kitchen without need for a pump.. A good trim carpenter can build attractive provision for mounting head inside perimeter of window.

Does anyone know of a good manufacture that might meet these height restrictions I have?

Manufacturers in the mini split realm are mostly a dime a dozen, because most 99% of them are made outside the USA. Even if the brand name is a traditional USA brand.

Things change so fast in the mini split market that what was once considered a good "brand" may not be the case because of the "model" of that particular brand. This is why it's mostly gopher whack-a-mole game trying to pick something because you heard it was a good "brand" by name on the side of the box.

When you have room restrictions, this will make the battle even harder. This is why you really need a local HVAC trades person to help you select the unit that is going to work the best.

Problems after the sale? parts? warranty related issues if they pop up?

If you just pick one without no local distributor support? The distributor is the invisible component to getting parts, not just warranty parts, but parts as the equipment breaks. It will break especially if you are putting this in a kitchen that is used to bake greasy things. That grease goes air borne, gets sucked into the unit. No brand name is going to fix that problem.

Other issues with mini splits is noise related concerns --- usually these are mostly noted for installations in a bedroom where people are sleeping. The development of clicking noises and other odd noises.

So in consideration of all these things mentioned above probably the best support / availability of parts and such would be Mitsubishi, however these are probably more expensive as well.

That said you need to make sure the manufacturer you choose has local distributor to you. While Mitsubishi is the biggest in this realm doesn't necessarily mean they are local to you. The mini split market in the USA is a tiny fraction of the HVAC market here.

How the unit is installed is important... probably the most important aspect of the whole operation above that of other concerns mentioned above. Things like having the ability to perform maintenance functions easily.

Which brings me to another con in selecting this type of equipment --- proper maintenance of the machine is required. Skipping maintenance will likely run the machine into the ground far faster than you can imagine. (These aren't like traditional ducted HVAC system)

Well, the usual suspects have weighed in without questioning whether the particular equipment will meet your needs. You indicated that heating is the primary concern. Keep in mind that the heat output of a mini-split heat pump (or any heat pump for that matter) is a function of outdoor temperature. You won't get the same heat output at 5 F that you will at 40 F so make sure the mini-split heat pump you are considering will meet the heating needs across the full range of winter temperatures you can expect in your climate zone. At temperatures below the cross over temperature (the outdoor temperature where the heat output exactly equals the need,) you'll need supplemental heating. Once you've determined the particular system will meet your heating needs, you can shift your focus to the dimensions of the indoor unit vis a vis the space available.

Mounting an indoor unit on an interior wall won't always require a condensate pump. If you have sufficient pitch from the unit's drain to the exterior you won't need one.

Your window has an at least 12" header than will be supporting the roof load over than window. You are not going to be able to have the height there that you think you will. You are going to have to pick another location anyway.