Chevy 4.3 L TBI injection- Help with mods

[fat_mac]

I have a 4.3 l engine and a automatic 4 speed transmission. i got it out of a 1987 chevy astro. i am putting it into a 1990 chevy pick up truck. I would like to Modify this motor without taking it to a machine shop or anything like that. i know i can put undersized pulleys on it and result more torque. does anyone know a web site that has a breakdown of what mods are possably and how much HP and tourqe they add. i am very new to the world of prefprmance auto's. any help would be greatly appreciated. thanks