The answers to a question like this usually amount to personal preferences, and I'm sure you'll get a lot of them, and there will be a variety, haha!

Since Acer platanoides is a bit of a hardiness experiment in your area, and those specific branches are "living their best lives", I would leave them, with a few caveats.

If the tree does well in the long run, grass will not do particularly well near the trunk. Develop a large and continously increasing planting bed, or just mulch (but Gaia hates a vacuum and will put something in it!) so you will not need to mow under those branches, or anywhere near the trunk.

I don't really like those branches being opposite each other for the long haul, however. This is mostly esthetic, but also a bit structural. I prefer to see the big, "scaffold" (don't know how I feel about that term) branches alternate around the trunk with some vertical space between them.

There also seems to be a bit of a conflict on the left between the big low branch and the one above it??

Perhaps take a look at that possible conflict and let that guide your decision.

But the fact that this tree has struggled in your zone might take precedence over having perfect structure, and you might just do minimal pruning to give it its best chances.

I do however think a large grass-free zone under the tree is, without question, the best plan, making your "so I can mow" comment less of an issue.

Excellent. Thank you. you have brought up some great points for me to consider

I dunno. One the the most impressive Norway maples I know is one near where I grew up and has one absolutely massive low but quickly ascending branch about chest high. The mowing issue isn't one at its age, because as art states, grass hardly grows that close to the base.

PS The one massive branch is on the leeward side of the trunk (opposite side from the prevailing wind).

As your maple grows there's a good chance you won't have to mow underneath, thanks to the nasty roots and dense shade with a smothering blanket of autumn leaves... but, if you'd like to remove the branches but they're more than you feel comfortable cutting off in one year, I would just head both branches back by half. If you keep pruning the lower branches back, in a few years the top will take over and you won't even think twice about removing what's left around the bottom.