Well DD the previous owner certainly did a job on the 100yard sight!
To me it doesn't look like the original full leaves & ladder sight that could have been on it; however the sight you have now is certainly been on there a VERY long time as it's patina seems to match the rest of the rifle.
No wonder you have agonised over this!
If you could get an original replacement with ladder it would be the ultimate replacement, but in my humble opinion I would only repair the existing (100 yard) sight if you could get it browned close to the original patina; otherwise just use the 200 yard sight & file the 'new' front sight (if you have to)like Daryl has suggested to use as your basic hunting sight - zeroed for 100yards.
Hope the eye ops & hunt goes well mate - wonderful old piece you have there & cartridge too!
It'll take anything that your country has to offer.