Double Eagle + orphaned engine = a winner?

After Bob Hoover's recommendation of the double eagle, I fond myself at
the DE website and thinking I've found my first (maybe only) plane.

I already have a stock 1600cc bug engine to use that is ready to put
together other than a few bits but I'd like to try Bob's suggestions and
go with the 78mm crank. Anybody have a good recommendation on a 78mm crank?

I will be turning the engine around and mounting the prop on the big
bearing end of the engine but I'm not sure how I'm going to do that
right now. The Great Planes rear drive looks overly complicated but the
only other system I've seen was on a German website a couple years ago
on a type 4.

I have an 1800cc engine sitting in a friend's basement (assuming he
hasn't tossed it) but I'm not sure if the increase power will balance
out the added weight. Then there's the high price of the 1800cc parts...

Suggestions, comments, slurs? Let me know what you think...

Tony