I'm selling a man a left hand Zastava M98 Mauser action and he wants to create a left hand 8X57 rifle and shoot it with 5 round clips and iron sights. Could the clip slot be milled in a commercial action? I know that there are no clip slot lips, but I suppose they could be added with weld if needed. Any suggestions.

Yes, the rear bridge would have to be welded up. Then contoured and machined to accept stripper clips. How much money has he got?

Just thinking out loud it might be easier to weld on a piece of mil 98 receiver with the slot and hump on it. I am not volunteering to do it.

There used to be available a commercially made adapter which used the scope base holes to fasten it to the receiver and which provided a perfectly useable clip slot for a rifle without one. I may still have one kicking around somewhere. It would mean foregoing a scope, but you can't clip load a rifle with a scope anyway, unless it's offset, like an M1C.

Does the front of the bridge in the mag well overhang the rear of the mag box? Need about .150" or so. If you have material there I can cut one for you. Have done plenty Remington 700's and Winchester M70's back in the day for NRA highpower guns. The trickiest part is getting the corners square and the locating tab relief cuts in the right place. Have a special cutter for that feature.