I am assuming that the rear sight is not adjustable for elevation. If I am correct, then wait for the correct sight. 1mm = .0394 (usually rounded to .040 ) which means the front sight will be .020 shorter than you need. Depending on distance, sight radius of the gun and so on, this can be significant.
I think you will shoot too high with that sight.
Maybe try to search different sources. Maybe there is some place else that will have exactly what you need. If you have an adjustable rear sight, then it is possible that the difference could be made up in the adjustment, but even that is not a guarantee.
I think you're best off waiting for the right part.
Good luck
Rich