You mean '57 G heads?
The cam may be fine, but it is a good time to upgrade if you're going to do it.
In general:
2teens @ .050" will have a smooth idle and be a step or two up from a stock cam.
220s @ .050" will have a definite performance sound and perhaps a slight lope and should be absolutely tolerable for a cruiser.
230s @ .050" will have a lope, probably about the borderline for what is tolerable for street use.
If you want to retain the 4.09 gear, you probably should go no bigger than 220s @.050, to have a better chance that you are in the power band while cruising in overdrive.
RE the advance curve, 36 degrees total, with 12-14 initial, all in by 3000rpm is a good starting point. Fine tune from there.
Lawrenceville, GA