Since you are planning a varmint rifle, it almost has to be scoped, so you need to decide whether or not you want to alter the original bolt to accomodate a scope.
If you should decide to go with a period scope, such as Lyman, Unertl or Fecker with external adjustments, you would not need to alter the bolt, so that choice might be a good one to consider.
You could also avoid drilling and tapping the action, since putting both bases on the barrel is an option, although you might have difficulty obtaining the ring spacing required for 1/4" clicks if you take that option, unless you choose a scope with an exceptionally long tube, such as a Lyman Targetspot, Unertl 1 1/4", or Fecker 1 1/8" scope. If you don't mind drilling and tapping the action, a Unertl or Fecker Small Game scope or a Fecker Woodchucker would be good choices.
You would also want to use a stock with a higher than usual comb to accomodate the height of the scope tube. This Griffin & Howe stocked Model B might give you some ideas about stock design:
