Towing power add-ons. I tried searching, words too short, or subject too old.

'99 Suburban 3/4t 4x4 350 vortec SCFI 5.7l 4L80e OBS. The only difference, as far as I can tell, in the towing capacity between my truck and the 454 is hp. So if I add a little more, I can pull a little more - easily.

-I want towing power, when I want it - and at least the economy I get now. (hand held power programmer)
(most people who tell me about custom tunes include their 1/4 mi time - it's 7k lbs, not a drag car)

-In the pre-pcm days, 350's got a rv cam and everybody was happy. As far as I can tell, Vortec's don't like new cams.
(I'll need to reflash, anyway, so I'd do a lot more than just a cam)

-What does anyone know of the marine intake swap? Drill out a couple of bungs and slap on some rtv?
(sounds good, but at 2-3 grand for the bare intake!? Hello big block!)

-Will the 093 corvette servo for 2-3 shift work in the 4L80e? or is that a 4L60e/700r4 thing?
(my tranny guy says he's heard of the swap on the 60, but has only changed filters on the 80. The C4 in my Mustang will break your frickin neck, though!)

-Will a Dmax/Alli fit in the frame rails of a '99 Burb
(yeah, right, I'll post pics...)

Thanks gang,