Speaking of economics, a cherry '57 Fisherman in my area can go for $500 or more with pressure tank in similar condition. If converted by a PO, motor might be worth $150-$200. Price is driven by collectors.
There is also a perception that conversions done by newbies are likely to be poorly done, run poorly, and maybe make restoration difficult (i.e., expensive, or likely a Frankenmotor with mixed parts).