96chevy

im looking to upgrade my 5.7 vortec in my 1996 chevy 1500 4x4. looking for something that will give me a good range from 900-redline in rpm range because it is a 4x4 and do some offroading and towing, plenty more power but i dont want to replace springs, rockers, machine heads, or anything other than basically replace the cam. i have dual exhaust and have ordered the headers. it is still my daily driver but just need to warm it up a little. kind of on a budget,dont' wanna spend more than $350. any suggestions?