Daryl is correct in the removal of lower lug metal, but I must point out that was how almost all 300H&Hs were made from the 20s to the 70s. Holland and Holland themselves, the inventors of the round did it that way on many guns. My own is made that way too. It's not a problem if the owner is not an idiot and if the gunsmithing is done correctly. The best way to make an H&H is to start with a magnum length action, but I am betting 75% of all that were ever made were not made on Magnum length actions.

The best way to make one on a GEW length Mauser is to move the back end of the mag box rearward as far as you can by milling out the rear end of the receiver to allow it. You can gain about .110" to the rear doing that. You must make a new "back end" but that's pretty easy.
Then you make a new front for the mag box so it's about .90" longer. Fit it to the receiver, scribe a line around the bottom flat of that receiver and mill or die-grind it away to re-form the feed ramp. The last thing to do is to lap the lugs back to the point the 3rd "safety lug" becomes a locking lug.

The lower front lug on the Mauser is the strongest of the 2 front ones, because it's not split for the ejector. But cutting back the lower lug area reduces that metal for the solid lug to lock against. The upper lug locks into solid and super strong metal, but the lug itself is a bit weaker because it's split.
But,,,,,,,, that 3rd lug, when it is made to lock is sold and locks into solid and very well supported metal. hence the reason for making M-98 into 3 lug systems when you can.

That how I have done it many time. All the action work including the lapping and the heat-treatment needs to be done before the barrel is installed. That way you set the headspace correctly after you set the bolt back to bring the 3rd lug into solid contact.

A 98 set up that was is EXTREMAL strong. Stronger in fact then the M700 Remington, M70 Winchester or Ruger M77, if the metal of the 98 is of equal of higher quality then the Remington, Ruger or Winchester. That is the reason I prefer the case-hardening approach to this work.
You can't always know what steel you have with old Mausers, but ALL of them are good enough for case-hardening and all of them are very strong when it's done right. The 91, 93, 94, 95, and 96 actions are all 2 lug actions, just like all the Remington 700s, M70 Winchesters Savage 110s Howas, Mossbergs and Ruger M77s. The 98 is the only one that is a 3 lug locking system of that bunch, if you must set it up that way or the 3rd lug will not lock anything.