Some 'prevailing facts' & thoughts re the "transition era "300 Magnum" as the factory 300 H&H chambered barrels were yet so marked.
First, the prevailing collector fact set suggests that your Model 70 in 300 Mag, of 1949 vintage should not be drilled & tapped. My nearest, of 1948, SN 110K range also is, but should not be even moreso! And with recoil pad. Being in decent used condition, a three time loser for collectability. The thought prevailing, factually a smaller bridge area of the magnum models, That as top mount manufacturers of the day not settled on a standard pattern. Such and demand being filled by both Stith and B&L. Both utilizing the aft receiver sight mounting screws which were ever standard on the Model 70 from beginning. Prevailing collector thinking, figuring about SN 169K, as I recall, before Winchester settled upon and routinely tapped the 'big mags'. The additional problem nowadays for your rifle and mine, given non-factory mounts standard, just what mounts they may have been drilled to accommodate! Hopefully done into the fifties as mounts standardized!
Realistically, some seventy years after production and the convenience of scopes pretty much SOP for decades now, few "original", untapped Model 70 rifles yet exist. Add too the matter of original finish in collector-acceptable grade condition.
My point, even if our rifle were "within factory correct specs, unless all metal pristine including original blue; paying an often-considerable premium for an original stock, Discrepant results! Best to carefully calculate the investment/return situation of investing in a decent, unaltered stock. Conversely buying a decent "also ran stock" in terms of with recoil pad, making sense. Where the metal isn't in collectible category, the H&H factory ammo with noticeable wallop. A pad makes sense. Just on average, expect to replace the more often than not aged & hardened pad. The caveat, once pad installed, don't depend on length not also 'trimmed'. You need to have the precise length of pull from which to decide whether such a stock will work for you!
Your rifle presumably retains considerable valuable for great pre '64 heralded "field use". Add the stock 26" barrel and svelte era integral forged ramp front sight... With customization as subset of that really nice mode! The "also ran" factory stock perhaps refinished, or opportune time for custom replacement! Many possibilities! If you're bound for 'collectability or bust', patch it up, sell it & start over!
A short moment for Attribution. Louis Luttrell, preeminent pre '64 Winchester Model 70 expert; such for his contribution concerning pre '64 model 70 "postwar transition era" scope mount situation. I'm merely pinging off 'the master'! "Non-collector aspect, as my take.
A few shots of my 1948, SN 110k. Yet if with new pad, a fine "field use" candidate! Best & Stay Safe John
