For what it's worth, I've never done the conversion you are proposing.
However, in
Australia I am a licensed
motor vehicle ( usually taxis) LPG (to you ..propane) installer. We convert cars from gasoline
fuel to propane. Despite having plenty of qualified experience, never ever would I bother to convert an alcohol
stove to propane. Not impossible, but I'd be eating and drinking cold things before I'd even think about this conversion.
Maybe in your part of the world conversion specialists exist and I hope they do.
But frankly, as already suggested, I'd somehow try to find the
money for a new propane stove.
Good luck which ever way you go.