First of all springs should not have a bend or kink in them. They will still work but not as smoothly/quietly as a straight spring.
Secondly you want to get rid of the sharp edges in the cylinder BEFORE you install a new seal as it can be cut by them when installed. Use a wooden dowel wrapped with sandpaper and a drill. Put a screw in the end of the dowel and chuck the screw.
Thirdly an ideal guide fits snug on an uncompressed spring. When the spring is compressed the inside diameter increases and allows for free rotation. When fired it decreases and tightens on the guide reducing vibration(twang).
You can use shrink wrap or just order a complete kit from Rich from Mich.
Finally as for a JM spring it is better quality and thicker wire than a factory spring. This results in more consistent velocities and a LONGER shot life.
In closing congratulations for learning how to take down and repair your gun