This is the same way I am thinking.. For the things you have done you picked up a decent amount of HP, basically (same heads, just raised comp) a cam and tune. The tb is neither here or there.. The bigger verter is not that great of a idea in a towing situation.. The bigger(lower) gears will help more then a converter, not hurt the trans.. If your looking for big block or diesel tq, your prob not going to find it in a 6.0, moreso in your 408 or a boosted app..

 

I would think it would make more mine made 403hp and 382 with my 4l80e and a 10 bolt but mine has l92 heads

 

Have any of you guys considered an add on overdrive? there is a quality one out there that lets you install it as an over OR an underdrive. 3.73s with a twenty per cent underdrive gives you 4.62 final drive, and with the low gear of a 4l60e that is some serious torque multiplication!
That is my plan when I rebuild my 5.3/4l60e combo in my 2000 1500 with 3.73 gears. You dont have the pain of setting up the rear end either.

 

^ I've never heard of this...is that really true? You aren't changing any of the hearing in the truck so how can you get a 4.62 ratio after that?

 

More gear and bigger convertor you'll be happy. but you gotta rememeber also...that truck with big tires...is HEAVY