if i were you and didnt have the mechanically ability to my own work I would pic up a low mile 6.0 and bring it to a local shop and get them to put a cam/springs/pushrods in it and dyno tune it.......... then save your money for a transmission

 

600hp is 600 hp. Your not going to get 20mpg with that kinda hp in a 5k lb truck.. What I said in my orig post is what I meant.. You do a set of gears, heads cam, FI you will have a pretty fast truck. But seing that you are not going to be doing the work, that would be costly to have done at a shop.. Even a engine swap is going to be $$ at a shop.. Put a converter in that thing, boost it.. In the mean time save for a trany.

 

Where are you located and what exactly are your goals for the tahoe what are you going to use it for?

 

Doing the work myself is out of the question; no tools, no garage and - the worst of all - no knowledge. I'm asking about options for myself here because when/if I go to a shop and as the same questions they might be presenting options, which are the best for them.

 

I'm in Chicago and as far as the goals: I'd like it to be fast (not the top speed but acceleration/passing speed wise), responsive and not a total gas hog. I will not be racing but I'd like it to behave (almost; I'm reasonable) like a race car. This is my daily ride.