I won't ban you for that, I used to do it myself.
The Mauser 98 is the one with the most options.
I've had sporter 98s, built off military actions in calibers ranging from .22-250 to .458 Win Mag.
Suitable Springfields or 1917 Enfields can also be converted into a wide range of calibers. Mauser style actions, including the Arisaka can also be used.
The other systems, like the SMLE or the Moisin Nagant or the Krag are best left on either their original calibers or suitable pressure wildcats based on the original case.
Since the Moisins are the most recent (and still the cheapest) aftermarket stuff for them is easiest to find, but with them, no matter what you do, you still wind up with a 7.62x54 Moisin Nagant.
With a Mauser, you can, if you invest the time, skill and money, wind up with a rifle the equal of about anything made during the classic era. Few do, but you could do it.
Absolutely not economical today, done right you will spend 2 or 3 times what the rifle will bring on the sale market, but you will have a rifle, done right, and done exactly the way you want it.
Good Luck.