Those steps are right on. You might find axle spacers at your LBS, but many don't have a whole lot in their parts bins if they work mostly on newer bikes. You can order them from loosescrews or biketoolsetc. I've resorted to 9/16" washers (I think - check the size), which fit pretty well and I can get in a box of 100 for little $$.
Redishing the wheel involves moving the rim (which is now off center, thanks to your swapping of spacers from one side of the wheel to the other) away from the freewheel side. You need a truing stand and a spoke wrench (or a selection of different spoke wrenches - there are different sizes). You might be able to do this job in the dropouts without a truing stand, but I think it would be difficult.
If this sounds daunting, it is, slightly. It is definitely time-consuming. The SS conversion kits you've seen only work on cassettes, not freewheels.