Caliber could be flexible depending on bulk of your use. I have one converted to 6mm, Shilen barrel, Brown Precision stock, but I think it's important on these to change the safety, and trigger. I went with a Gentry 3 position safety, and Canjar many years ago.
So I guess I'd say it can be a rabbit hole experience if you aren't careful.
The .350 Remington requires a bolt face change, the .35 Remington too anemic for me. The .358 Winchester would hold some appeal, with either the 173 Sledge Hammer or 203 Sledge Hammer. Depending on how length all came together.
I'd probably go with a standard .308 myself.
I'd put a rail and reflex sight on it. Cut it for a kid, can't get the adults to leave it alone.