One that I will probably not make for myself, but I have done some for other people (and REALLY liked the way they came out) is a CZ 527 converted to 6.8SPC. I don’t have time to do one for myself, or the money, but if I did............................

You need a M-527 in 223. Used ones can be found for about $350
You open the bolt face up to take the 6.8 shell. It's just like opening up the bolt on a standard Mauser to fit a belted mag. But on a smaller scale.
Next you screw in a 270 (.277") barrel. Get one with a 1-12 twist if you can, but the 1-10 is fine too) Then you buy the M-527 magazine and bottom metal from CZ-USA made for the 7.62X39 shell. It feed the 6.8 fine.
Last your restock it in a nice fancy piece of walnut and slim it down to a very petite size. Install a set of Weaver #39 bases on the flats (I don't like the CZ rings because they are designed to fit men with necks like a giraffe) and set a compact 3 or 4 power scope on it. You end up with a rifle with the same ballistics as the original 257 Roberts shell but with only an 18” barrel, and it weighs only about 6.5 pound field ready.
The last one I did was for a 14 year old girl in Oregon and is a real gem. And it shoots well under 1" at 100 yds.
110 grain bullets at 2820 FPS