Hole in the solid wood floor (1940s)

[Malgomaj]

Hello!

My wife and I have moved into a house from 1947, and in the dining room, there was a laminate floor that concealed an older solid wood floor, something that became apparent after unscrewing the threshold strip. Since we preferred the older wood floor, the laminate floor went out the window. When the laminate floor was gone, a small problem became apparent.

In one corner of the room, there was a rectangular hole in the wood floor, patched with unplaned wooden planks of a different width, with visible nail heads. This patching was likely not intended to be seen, but something done in preparation for the laying of the laminate floor in the early 1990s, I guess. Maybe there was previously a built-in cabinet or something similar, hence this solution. Whatever the case, this must be addressed for aesthetic reasons. We want to lay a new floor in this "hole" that matches the older wood floor as closely as possible before a future floor sanding. The wood floor has dimensions of 28 x 62 mm (thickness and width).

As a new homeowner, my knowledge in this area is very limited, so I hope you can point me in the right direction, even if it means hiring professional help from a carpenter.

I have taken photos of the room to clarify the whole thing:

Here's what the wood floor looks like (sorry for the mess):


Here's what the patching looks like:


Here's what the mismatch looks like:


Here's how the wood floor is laid:


Now to my questions. The overarching question is of course: "What do I do now?" but more specifically, I wonder:

1. The original wood floor – is it pine or spruce (I guess pine, but I wasn't a star in woodwork)?

2. I can't find tongue-and-groove pine flooring in the current dimensions. Is it an idea to special order, or is it an expensive undertaking?

3. Could another solution be to use untongued boards and screw them down with a few millimeters in between, then caulk the whole floor (including the original floor), and finally sand it down? Possibly lay a board of some kind under the newly laid area.

Yes, my thoughts are kind of scattered. Grateful for any tips.

Viktor