I suspect that MTH doesn't do upgrades simply because they had their plate full with repairs, etc. I'm personally not worried about them taking business away, I can't do the work that is already knocking at the door!
Still have two months of backlog John?
Nicholas Smith *did* have the 50-1911 steam upgrade kit available on their website, having personally bought two in the past month, i should know.
EDIT: wow, I was copying the link, went to grab a quick drink and in that span, it went from one left to out of stock. Sorry about that!