If that's the direction of your build, I would suggest the 98 Mauser action in the .300 H&H Mag. Plain stock, tight grained walnut to absorb recoil. Bed it for sure. No fancy checkering or spacers or caps. I'd suggest a leather-covered recoil pad as it was 'de-rigeur' back in the day. Esp with a hard-hitting caliber. Three blade Express sights, a must. There is a place in NH that sells really good QD scope mounts... but I can't think of the name of them. They did all the stuff for my Mauser. And when a screw fell out a week before i was off to a hunt, I stopped by on no notice, they not only replaced the screw, but went through the whole rifle, while I waited, and charged me... nothing!
For a scope, I'd consider droping the Leupold idea and look for a 4x or 6x Kollmorgen. They were period and were rock solid scopes with an amazing back story... made to keep a submarine periscope plant in business in the '50's before the first 'nuc boats. They later sold the design became the Weavers, I think the K4. But the quality of the Kollmorgens is awesome. You can get dot, post or crosshairs reticles. I suggest dot or post on an Africa build. Will take you some time to find one... and you may have to have it cleaned/restored. They are amazing scopes. I run one on a vintage Sako and it is most excellent! Other than that, in the era, the only really self-contained scopes were German. That would be far more in keeping with the period than a Leupold. Old German scopes are spendy... but restorable and gorgeous.
Simple leather military sling. Buy it now and start oiling it so that when your gun is done, the sling is butter soft. That will take 2 years!
Get a good set of dies. You can always load the H&H cartridge down to .30-06 velocities for target shooting, plinking and barrel longevity!
It's what you want! Build your dream and we'll be interested to see the progress! Go For it!!!
Cheers,
Sirhr