As long everything except the solid-colour parts of the vector drawings are transparent, and in a PNG format, this should be perfectly practical.

Not sure exactly what parts of the process you may need help with, but perhaps these two half-hour video tutorials may help:

Symbols - Part 1: Finding and Preparing Images

Symbols - Part 2: Creating a Symbol Catalog

Jim, I think your original maps are from the Argan Argar Atlas, which states only that the hex scale is 8 km or 5 miles. All that means is each hex is classed as five miles in size, but that's NOT in any specific direction. This was a very common assumption at one time, when hexes were really just used for approximate distance estimating in games overall (RPGs and boardgames), so it's not a true scale from any one part of the hex to another.

It doesn't help that even some of the original hand-drawn maps of Glorantha by Greg Stafford don't have a proper scale on them, so realistically, you can set whatever scale distance best suits your purposes, and not get bogged down in the minutiae of mathematical precision for something that never had it in the first place!

If you want to investigate further, this topic on the Basic Role Playing Forum (for those unfamiliar, BRP is the base RPG system engine all the Chaosium RPGs use) pretty much covers all the essential details and issues. Even the official published RQ books and maps aren't consistent in their scaling of the same places - which to an extent is fair enough, as this is a game world set in what for Earth would be the Bronze Age!

Not sure if I'm interpreting what you're intending here correctly, but if the paler, sandy coloured coastal strip is meant to represent an extensive, low-lying beach, and the fractal lines are the actual high vertical cliffs, it might be useful to use the cliff lines as the coast, and make the seaward edge of the beach have a less strong outer effects line. If it's a beach, after all, it must be submerged by the tide in part at least some of the time, whereas the cliffs would form the actual coastal barrier.

The only real use I've ever made of iso maps is as visual aids, although a lot of the earliest were really illustrations of buildings/locations, not true maps anyway, and done in a fully artistic style. The first actual iso maps I recall were from the original Castle Ravenloft maps from TSR, which also included some iso drawings. This concept followed through into the original "Ravenloft - Realm of Terror" boxed set, which had both maps and building diagrams done in an iso projection, as well as more traditional top-down maps. That would be in the late 1980s and early 1990s.

I really wouldn't want to use these as tabletop battlemaps though, as the whole point of those is to show exactly where everyone is, and as iso isn't the easiest projection on which to visualise such things, I always found it better to avoid that.

This is all from many years ago though, and only as in-person visual aids, so things, and people's expectations, may have moved on. I know some of the VTT set-ups allow you to visualise layouts in a mobile fashion, almost like real-world settings, so anything from top-down to side-on, or even from below, and that can be useful for helping people visualise what's on walls or shelves and in cabinets, for instance, as well as judge angles of slopes better. That though only really works if you're either online, or have a large enough screen that people at a table can all see equally what you're trying to show.

I was actually thinking more about the topic title than what the style might contain, Sue, in case someone's trying a search in future for something for elsewhere in East Asia than Japan.