ORIGINAL: Silvaire
Fella's,
Before you deflower one of those NIB O.S. FS20's, do a little research on their value. These little jewels have become popular with the engine collectors. I do feel that engines were built to RUN and have FUN with, but I don't think there is really anything that the FS20 does particularly well. An FS26 or a Saito 30 probably weighs almost the same but has more power - and especially so the Saito. I think there may also be a four stroke Magnum .26 clone available too.
I was going to say the same thing, although not as vividly as you.
The FS26 is also no longer made, but the FS30 is a great little engine. Another option is the Magnum .30 4 stroke. According to the specs it's actually lighter than the OS, but a bit heavier than the Saito. The price is certainly better than either.
I'm 99% certain that if the OP does a search he will find some threads where people have put a .30 4 stroke in a mini-funtana. From what I remember, the results were positive. Every time I see one at the LHS I'm tempted to do this very thing.