Drilling it again for top-mount Weaver bases like those in your last photo is my fallback option.
I think this would be your best bet. You could always plug the current holes, and then have the receiver correctly drilled & tapped....it certainly won't hurt the value anymore than the current holes. Looking at the receiver in your pics, it appears to flat along the front and rear of the action...not sure why you couldn't simply have it tapped for the base sets I have and use them for the front and rear. If you decide to go that route, I'll send you two sets to use.
