RE: curare restoration
Chris,
if the engine is pumped then you'll need the 86 otherwise keep the 7L.
Yes, there is much difference between the standard RF and the Hanno version. They're designed for different props and RPM peak. The latter also is more powerful.
I don't think you'll find the header commercially for the RF to direct the exhaust and pipe under the wing but you could have it custom made. A Webra Speed 61 or an OS 61 SF might be better candidates if you want to run the pipe as per the original. The RF is better suited for an upright or inverted mount configuration in a design which has a pipe through the fuse top or in a wing belly pan on a "mid-wing" design.
David.