Eric Lowe wants better fuel mileage -- who doesn't?  You could probably adjust
your accelerator cable real slack, so that when you floor it you would only
get as much performance as you used to get from the Type 1 engine.  Putting
a Playmobil pirate under the accelerator has roughly the same effect.  More
seriously, you can tinker with the carbs and make sure your engine is set up
right (valves adjusted and good compression), but you'll never match the
mileage of the smaller engine unless you never use the performance of the big
one.  Moving up to a late 70s FI engine is a near-boltin swap (fuel return
line is the biggest problem I can think of) and would give better mileage
with comparable performance, but not cheap.

Rev that sucker and smile.  If you still had the Type 1, you wouldn't be here
yet.
B.