With the drum turned and new shoes you are going to improve your braking. If your drums have been turned out too far they heat up faster and fail due to heat faster.
But they are going to be no where near as good as discs. Going down long winding hills for instance use to smoke the brakes in my Skylark. But driving as I do with my Rambler every day, the little drum brakes are plenty because I don't drive fast or on hills. I have had a few real life panic stops without a hitch, it actually stops damn fast, once. But if it were asked to do that over and over they would smoke just like my Skylark going down a long winding hill. But for me they are plenty, that isn't for everyone.
I put front disc brakes on my Gran Sport because it has much more power and I use to race it at the drags, but the driving I do 99% of the time the drums would have been plenty.