Thanks for all the good advice on my power budget and alternator sizing.  It
will take a little while to digest it all, but I still have a few weeks before
I need to walk over to Bill Bainbridge's booth at Oshkosh and buy an
alternator.

For Shannon -- no, I was going to use the antediluvian vacuum pump approach.  
This saves me about $2000 on gyros ($500 vacuum gyros vs $1500 electric
gyros) and eliminates the complexity and cost of a dual electrical system (whose
extra cost is probably comparable to a vacuum pump system).  Since my IFR plans
are rather limited, and there are now vacuum pumps whose vane wear you can
measure, and I plan to have a low vacuum warning on my Jim Frantz annunciator
system, I think the risks of a potential vacuum failure are small in my case
(note to all -- your case may be different).  I certainly understand why folks
choose all-electric, and have no problems with this approach, but I'm choosing
not to do it.  

- Rob Wolf