Hey Mike,
There is a new in box webra rear exhaust on ebay as we speak. Going for $25.00 at the moment. I have a OS 60 ABC RFP new in box too, and it does not have a flake of rust on it.
I hope you build the Curare, I've had my eye on building one since 1981. I came very close to buying the plans last month. Someone in SPA (Steve Byrum) built a Curare, and put a .91 four stroke in it (yea I know). He did have a Rabbit, and he said the Curare flew much, much better. BTW I know where to get the cores if you don't.
You are right, It is amazing how well you can fly when money is on the line
Greg