To the OP: The first question is do you want a left or right hand build ? IF you are O.K. with a RH build, the Winchester is an O.K. place to start. You already have it. And the one Pre64 M70 I have owned (purchased used on GB) was one of the smoothest actions I have owned.
If you want a Left Hand build, the Pre-64 M70 is a good piece to sell to generate cash. If it is in reasonable condition, you should be able to land within $100 +/- of a decent LH custom action (MRC or Stiller). As stated above the Rem 700 wins the after market parts availability hands down for "options". the stiller is a Rem 700 clone. So most 700 parts interchange without issue.
IF you want CRF, MRC actions are Win M70 clones (+/-) and depending on the phase of the moon, anywhere from a little less expensive to a LOT less expensive than a true LH Win M70. But, if you luck into a true LH Win M70 for a reasonable price, it's workable for a build.
Personally I act as a "general contractor". I do simple work like swapping stocks, scopes, mounts, bottom metal, and Rem 700 triggers myself. However, I have had a professional gunsmith re-barrel every rifle I have changed the tube on. Remington and Winchester generally require some amount of lathe work to properly fit and chamber. I am not going to change enough barrels to justify the cost of lathe and then learning to use it. Easier for me to job it out. Cerakoting and hydrodipping I job out also.
The only caution is ... beware ... it is addicting ...
