I missed the fact that it did several resolutions in my earlier reading (though information about the card is hard to find). Thanks for the information. NICE when people are helpful!

That card will support my preferred monitors nicely, it transpires: a portrait display, or a Radius two page greyscale, or something like my 14" AudioVision for colour. The idea is simply to max out a IIfx, or possibly a IIci, with period hardware that works in System 6.