Does anyone have advice to build up the top end on a Chevrolet 2001 496 ci big block in our tow suburban? I would like to stay heads & valve train up. Ethanol ideas or links would be even better!!  

Umm...

Leave it the way it is! How do you need more power? What are you pulling?

Besides, the 8.1L is a Gen VII big block engine. Aftermarket camshafts and heads are VERY limited, like non-existant. I know Comp makes a couple hydraulic roller grinds you could look at. As far as I (or Raylar) knows, there is only one aftermarket aluminum head available but this may be overkill (and awfully pricy) for a tow rig. This is meant for a dedicated high performance ride and requires a reprogram of your ECU.

http://www.raylarengine.com/index.html  

Hate to say, but he's dead on above. Performance parts for the 8.1L are pretty limited. Because of it's limited use and lack of availability for hot rodders, the aftermakret hasn't seen a need to put a lot of development into that motor. I think Comp and Crane have a few grinds for them cam wise.

On the heads, your best bet is gonna be to take hte stock heads to someone and have them do the usual porting work.  

Just to add to the dilemma, realistically the "usual" port-work can't even be done. The heads are a "swirl-port" design, i don't believe it's as severe as the Gen 1.5 small blocks but it still makes the port junk to a performance rig.