Planning rebuild on 89 chevy suburban? torque

Wanted to see if you guys could give me some ideas on my rebuild.I am preparing to rebuild my 350 fuel injected suburban.Not wanting to make 600 horses out of it,all though that might be cool.:D I want low end TORQUE ! I plan on pulling car and boat trailers long distances ,and short ,and also have great gas mileage!I will get specs on the heads,and engine when I get back into town. Right now the only thing I know has been changed from stock is the edlebrock intake,and by the looks of how well the truck was maintained it might have a edlebrock cam.It has a 700r4 trans also. First off ,I am going to port match the intake ,and heads.Then a 3 angle valvle job.Will installing headers help for torque?Anyone have any ideas on engine combos,like cams and compression,and gearing that will work with the 89 computer?Thanks

See combo #11
http://www.ryanscarpage.50megs.com/combos2.html