Unless you have a talented machinist who will also work basically for free, this project has a reasonably high chance of failure. In addition it would almost certainly ending up costing more than the other proposed ideas here, even with the use of the 700 actions you already have.
If it was me and I wanted a compact rifle but wanted to use some of the random 700 actions you had floating around, I would just put together 2 rifles, one in each caliber, with a Remage barrel nut and a lightweight folding stock/chassis.
If it was me and I wanted a compact rifle but wanted to use some of the random 700 actions you had floating around, I would just put together 2 rifles, one in each caliber, with a Remage barrel nut and a lightweight folding stock/chassis.