@ koszer - thanks for the links and the part number, that has helped a lot, and the YouTube video is basically what I suspected would be OK to try, so all that's good, and very helpful, many thanks.

[UPDATE] - I've installed an A1027 Airport Extreme card successfully on the A1177 running on a Mac Leopard installation, so I don't see any reason it wouldn't get recognised under MorphOS, and I only needed to plug into one of the USB ports a standard PC USB2 bluetooth dongle and now there's bluetooth on the Mac, so no need for one of those overpriced "Runway" cards that I'd otherwise probably have to import from USA, and pay customs duty on, along with shipping costs, which would probably push the total price for a small PCB to $100 or more.

The only issue with the Airport Extreme is finding a way to get the older aerial connector to connect with the button type (female) connector that are pre-fitted in the A1177 PowerMac, but I managed to find in my PowerBook parts a small board, Apple part number 603-5812, which seems to be from an A1106, that has an Airport Extreme aerial plugin connector and a male button aerial connector on the small PCB, so they connected up quite easily, as I was expecting to have to solder on one of the connectors which I knew would be very fiddly/tricky, so it's all worked out nicely.

I've added this information on here so others know it is possible to get both WiFi and bluetooth in the A1177 PowerMac, for quite a small amount, and without having to use a "Runway" card.