Surprisingly, the stock Vgon engine is not horizontal front to rear.  On my
first installation I put the Porsche engine in at almost the same angle, and
had problems with muffler interference with the body.  At that setting you
need about 4 inches more height for carburetors, 6 or 7 more for CIS.  The
fan needed less than an inch.  On second installation (the 2.7) I dropped the
rear of the engine 2.5 more inches, solving the muffler problem.  Now the
fan is no problem, low profile air cleaners would *probably* fit, and the CIS
(when I put that on) will probably need just 4 inches or so of the 8-inch box
that I put on my engine lid.  It's the induction system that causes the height
problems, so I think the 911 engine is taller than either 912 or Type 1.

The engine hanger I made is a 3inch box of 1/4inch wall aluminum, running from
one frame member to the other.  Cutouts in it to fit the 911 engine mounts and
the stock 911 rear engine brace.  Someone who can weld would be able to do
something much more elegant.  Also Martin Schneider Designed Systems sells a
brace and precut sheet metal as a part of their $1700 kit.  For my sheetmetal,
I just cut cardboard templates and made sheetmetal addons to pop-rivet onto the
stock Porsche sheetmetal, which is consistently too small almost the whole way
around.  The stock VW engine seal is really good -- will seal anything from 
about 1/4inch to almost an inch gap.

See how easy this is?
B.