I don't think the 500 single should be ridden much above 55 mph, no matter what cam is in it. One reason for that is it's overall poor build quality and materials. It is also an ancient design. It works wonderfully when ridden at the speeds it was originally designed to be ridden at. A long stroke engine will always have a lower redline than a short stroke engine. It will have more low end torque, but less total hp. But like I said, power is not why I ride motorcycles. I ride them for the experience. The feel and sound. At 55 mph you can almost count the firing pulses of that long stroke single. It doesn't sound like a sewing machine like "modern" short stroke engine. The only other new motorcycle I like the feel and sound of besides the RE 500 single is a Harley Davidson, and I own a 1200 Sportster. It is not powerful or fast, but again it provides that wonderful feel and sound. And unlike the RE, it will easily keep up with highway speeds without self destructing. But it is more fun being ridden slower.
As for carburetors and points, there is nothing wrong with the concept. Vintage bikes had poorly designed and poorly made carburetors and ignition systems. With modern designs, materials, and manufacturing methods it is now completely possible to build a carbureted bike with a points ignition that would run almost forever without problems. The Amal carburetor on my RE, and the Keihin and Mikuni carburetors on my other bikes work perfectly. From 1200 feet where I live to over 8000 feet. And there is no reason they cannot continue to do that for the life of the engine. My 1964 Ford has been running fine for more than 5 years without the points being touched. I probably should replace them soon. True, new points and condensers are probably a great deal more reliable than those made in 1964. A modern points system could be made to last 20 years and 200,000 miles without attention. And yet still be easy to maintain and work on, and cheap to repair if something did go wrong. Don't let problems with poorly designed and built ancient carburetors and ignition systems make you believe that the concept is bad and that new electronic technology is needed. It isn't. What's needed is better designed and built carburetors and ignition systems that work the same way the old ones did.
Drum brakes. Yes a disc is somewhat more efficient than a drum. And on some bikes it's even a good idea, at least in the front. Nothing but large touring bikes need a rear disc. I have never ridden a bike with rear drum brakes that I could not easily lock the rear wheel on. About 90% of the braking is done by the front brake anyway. The rear brake is just for fine tuning braking control. As for a front drum, I have had a number of bikes with those, and could lock the front wheel on all of them. Something that is almost impossible to do on the RE with a disc front brake. Drum brakes look way better than disc brakes. Disc brakes are downright ugly. And on a motorcycle they are right out there for all the world to see. No they don't belong on high powered sport bikes (but then I don't believe bikes like that really belong on the road anyway, they were designed for racing) or big heavy bikes. But on a RE 500, a well made front drum (like on Japanese bikes) would not only out perform the disc that is on the UCE models, but look 10 times better as well. A lightweight 55 mph motorcycle does not need racing brakes. If you can lock the wheel, you have enough brakes. You just need to learn to stop without locking the wheels, rather than having a computer take over and do that for you. Being in total control of a machine is a huge part of the enjoyment of riding. Learning proper braking, throttle control, shifting, etc. is not unlike learning how to play a musical instrument. I don't think that playing a guitar (which I used to do before I got hit with arthritis) or a piano that corrected your mistakes would be much fun, since it would require very little skill.