OK report back.

Success on first file attempt.

File properly created, imports into TsmuxeR fine and produces a fine .iso.

A slight sync issue on playback thru the Dune media player and Marantz av receiver but I'm unsure if that's a big issue as yet (I did read earlier posts some people were experiencing this).

Nonetheless a brilliant workaround to my problem and I really don't know where I'd be without not only people developing this stuff but also the support network here who've helped. When I'm through Eurpoe next this Mac tragic definitely owes people here a kofefe.