"The best thing would be to somehow convert the GM soundfount to DXI somehow (not a clue how to do this)."
DirectiXer seems to have gone out with the Ark, I found LiveSynth Pro you can try, it's also redundant.
They all say DXi went out with the Ark also.

https://www.dropbox.com/s/uo1vwtlb163m4el/LiveSynth%20ProDXi.zip?dl=0

I would look at upgrading to Kontakt.