The fact that you need corrective lenses will not keep you from using aperture sights successfully for olympic style shooting at 10 meters. I'm not even sure where this idea came from. I have always needed corrective lenses, for nearsightedness when I was younger, and now for farsightedness in retirement.
What target are you trying to use? The standard 10 meter target is an approximately 1 1/4" black bull printed on 4 X 4 card stock. It is designed specifically for use with aperture sights. In use all you will be able to see is a somewhat fuzzy black bull on a light background. To aim you only have to position the bull in the center of the front aperture.
The sight set on the 300s provides two apertures, one at the rear and another at the front. You look through the rear aperture, and center the bull in the front aperture. The standard rear disk is a 1.1 mm. The smaller the rear aperture, the sharper the apearance of the front sight and bull. The larger the rear aperture, the brighter the sight picture. A 1.3 mm disk works best for me. If you do use the 1.1 mm standard disk, I would mount the rear sight as close to your eye as practical.
The front aperture needs to be big enough to show a well defined white ring around the black bull. On the standard target at 10 meters, something around 3.6 mm should be fine, although some people prefer larger or smaller. It would seem that smaller would be better, but for shooting offhand you need to be able to see the bull as it moves into the center of the front aperture. The general guideline is that the front aperture is big enough that the bull stays inside the aperture ring during your hold. I don't know what front apertures came with your 300s, if you don't have one in the range of say 3.2 to 4.0 mm, you are going to need to find a set or buy an adjustable front iris. If the adjustable iris is more than you want to spend right now, the clear apertures in 18 mm size will also work with the FWB front sight.
That is all you need to get started with your 300s at 10 meters. If you find you enjoy that type of shooting, there are a whole host of accessories you can buy from places like Champion's Choice that promise to enhance your sight picture, including rear irises with both adjustable aperture and diopter correction to allow you to dial in your plane of focus between front sight and bull.
Good luck, and enjoy your new acquisition!
Im thinking a diopter would be useless for me unless there is something I can do to magnify the diopter like a 1-4X scope. Is there hope for me or is this yet another thing this old fart needs to give away to waste on the youth? Maybe my vision will improve after a couple of whiskey tumblers? 
