The spot welded scope ramp on the MK3, was only designed for very light telescopic sights, which were common back in the 1960's and 1970's. I would not recommend fitting a modern telescopic sight to it as eventually the weight of the sight will pull the ramp away from the cylinder. This will snap the spot welds and the whole thing will fall off. If you do fit a telescopic sight then only fit up to 4X28 power as this is still light enough not to break the welds.
The open sights are very accurate, but do require a fair bit of practice before you can compare the accuracy to that obtained when you you a telescopic sight.
I personally line up the fore sight blade in the centre of the 'V' Notch on the rear sight, making sure that the top of the fore sight is level with the top of the rear sight. Then through careful adjustment I then set the point of impact at the top of the foresight blade.
So that when the open sights are lined up you still have a complete view of what you are shooting at. If you do what many people do - YOu line up the sights then obscure the target you are shooting at with the lined up sights, you cannot see the target properly and lack of precise shooting results.
Good luck
Lakey