What kind of range/yards to you plan to shoot?
I just did this today (Sat June 7).
You might take a look at: OpticsPlanet.com | Low Prices, Free S&H on Binoculars, Sunglasses, Night Vision Goggles, Riflescopes, Flashlights, Rangefinders - Hunting, Outdoor, Science & Military
Walmart also sells for OpticsPlanet and sometimes you can get better deals. Just know what you want by part number and be sure you are getting the same products.
They have lots to offer and some rings and rails have drawings so you can make an intelligent guess as to whether it will all fit.
I wanted mine as low as possible. I wen with the low rings, 3-9x40 which uses an external dia of 1 31/32" dia Objective dia scope. I went with a one piece Picatinny rail and do like the stability of the one piece. The rings are QD (quick disconnect) which I like. If I had it to do again I think the only change I might make is get the 2 rings connected together - like this:
I had the same concerns - scope diameter too large for the rings/rail combination but it worked out quite well. You should be able to find the dia of the 50MM lens.