The donor rifle in question was a small ring 98 or a ground large ring 98? My thought was that it was a Danzig small ring 98.
Regards what you're after my suggestion is a Griffin & Howe style carbine with Mannlicher stock and Redfield peep on a 20 inch barrel. Because you're using open sights your stock measurements will be more important to pointability and balançe than a prone shooting gun. I would tune a military trigger and keep that simple or switch out to box trigger. No point in spending effort on anything other than BYF, FN, Husky, Oberndorf undrilled action. Wood is as cheap or as expensive as you want it regards raw material.
If it was me, undrilled commercial 96 or FN 98, full length wood, 19 inch barrel, Redfield style rear sight, use the sights from your bad donor on the barrel. Cut down a Brazilian 1908 for instance and let the onlookers weep in outer darkness.
Or on another wildly different tangent, based on your requirements, a factory style Mauser 71/84 sporter with full length stock. Those actions are already case hardened.
On my own to do pile I have a first year 98 action with shotgun bow and a mint Argentine 7.63 barrel, with an original coffin bottom metal and sporter stock I'll splice a full length forend onto. I use fairly extreme stock dimensions and this stock works for me with approx 4 inch pitch and existing cast-off.