It'll increase your ease of towing and the amount you can pull, however not increase your safe tow limit.
A stiffer leaf pack (chev 1500) or AAL would help with sprung weight however your brakes will play a huge factor, also the fact you still have a very light compact truck, going over the weight of a truck this small is never a smart/safe thing.
But to answer your question, yes, depending on your transmission you will see a big gain in towing strength if done properly. If you have an 8.8" you'll be fine, and trailer brakes are a must for (IMO) 3,000lbs+ to be able to stop safely.
BTW - Air helper bags are a big help, but don't forget the esentials.
2000 Ford F350 - 7.3L, 4x4, 6-spd
"It's not leaking oil, it's sweating power!"
1994 Ford Ranger - built 306 SBF project street truck
2006 KTM 525 EXC-Racing - supermoto and dirt bike