Hello wislnwings,
Likewise, I am very fond of peep sights (great minds think alike).
Redfield and Lyman both used to make all steel receiver sights to fit the FN Commercial Model 98 actions, so popular before manufacturing costs became too high and these actions stopped arriving in other countries by the hundreds, if not by the thousands (the good old days).
Anyway, the Mark-X (Interarms) Model 98 action is drilled and tapped on the right side of the rear receiver ring, with the exact same pattern as the good old FN was.
In other words, the Interarms will readily accept the above two vintage receiver/peep sights.
(But, these type of sight require a notch be carefully cut out of the stock to fit the "block" that contains both the mounting screws, as well as the elevation adjustments).
Unfortunately, when you find either one these days, such a finely made sight will cost between $100. and $200.US dollars.
www.gunsinternational.com is where I have bought several such receiver sights over the years.
After I have determined my correct receiver sight height, (to match my front sight and my shooting style), then I like to install a rear scope base on top of the rear receiver ring that, has been ground down to just contact the underside of my receiver sight.
That way, if the sight is bumped, it is less likely to become damaged.
Back when I was hunting and informal target shooting a lot more than I have been lately, I have done some very fine work with an aperture sight on several of my rifles.
My first one was a Smith-Corona built 1903-A3 Springfield .30-06, that I bought for $40. in what appeared to be unfired condition, when I was 16.
I left it all original (did not "sporterize" it) and among other amazing shots with this rifle, I many times squarely hit long range ground squirrels with it, in northern California and Nevada.
Likewise, the peep sight was very fast to pick up erratic running jack rabbits with at close range.
Most people do not appreciate how useful a properly installed and regulated peep sight can be.
I look forward to seeing how the sight arrangement turns out on your Whitworth Mauser.
They are very fine rifles for an affordable price.
Cheers,
Velo Dog.