I don't know what sort of rifle you want to build.The Montana Rifleman makes a M-70 clone.There is a website .He makes barrels,too,and will fit and chamber.Brownell's sells CZ's and maybe some Rems.Seems like Brownell's or Midway sells Rem 798's and 799 mini-mauser bbl'd actions.I think Savages and Rugers are available,too.
If you are talking about extreme accuracy single shot rifles,try getting some issues of Precision Shooting or The Accurate Rifle magazine.
Milsurp actions ,try SARCO ,J+G,Springfield Sporters.
I will suggest,unless you want to make a beater utility rifle,or just want to do an old school experience,the milsurp route may not be the best choice.