To have a 'scope properly mounted to a Mannlicher Schoenauer (with claw mounts) will likely cost you at least as much as you'd pay for an MS without one. Vintage 'scopes themselves have become rather pricey in recent years.

If it were me I'd go with Skeet's advice and find an MS with 'scope already mounted. The pre WW2 'scopes were generally 4X or less magnification and often equipped with the post reticle which allows for quick sighting and ease of use. The quick release feature of a claw mount (or a 'Vienna Snapper') is also of great advantage as it allows for use of 'stripper clips'.

If you're considering the addition of a 'scope but are hesitant to modify an uncut original 'prewar' MS sporting rifle or stutzen (as I would be), you may consider a 'sporterized Greek' MS built on a military Y1903, Y1903/14, Y1903/14/27 ('Breda') or 'System 1930' as those models were all on the same 'action' as the M1903 and are 6.5X54.

Zeiss - My M1910 has a Gerard B with the 'No. 1' reticle shown here

Claw mount for Mauser - note 'see through' rings for iron sighting with 'scope mounted

'Vienna Snapper' on MS

Claw mount (on MS) by Dorleac