I would say going from gas to glow is easier, less expensive and worthwhile than the other way around. Even then, do it only if you are the tinker type and don't mind spending a whole lot of time figuring things out with potentially so-so results.

I converted several weedie engines to glow. You really only need to get a glow plug adaptor to make it work. I got mine from CH Ignitions. I talked about my Ryobi 31cc glow conversion a while back somewhere in RCU. Ran it on "4stroke" glow fuel (i.e. 15% nitro 17% oil) and it puts the OS 1.60FX to shame for less than 1/2 the cost. It also ran just fine on 5% oil and no nitro, though power was not quite as good as with a little nitro. Weedies are by nature built with low CR to withstand the abuse of clueless home owners and year-old bad stale gas. You need some nitro to wake it up a bit.

You will get better answers by posting this kind of questions in the Conversion forum.