If there is a ridge you've probably got some cylinder taper. Round straight cylinders are one of the most important parts of making power.
you can get by doing just a rering but the motor won't make the power it should.
The first mule I put on my dyno was a 440 I reringed. I knew it had alot of cylinder taper but needed a real short term quick fix when I did it. The dyno opened my eyes, the motor made pretty good hp up to 3500rpm, after that the ring seal started to go and the hp numbers went right down the crapper. The motor had so much blowby under load from the dyno it pushed the steel intake gasket up against the intake manifold.
I would have the bores checked and if it needs a rebore look around, e-bay, here on Moparts, racing junk,ect., you should be able to find a set of cheap pistons. Dave