What is the best method to drop my truck?

[1bad84silverado]

First off I'd like to introduce myself I'm from Kyle,tx and just acquired my brothers 1984 Silverado so I'm new to the truck seen. I like to lower my truck probably a 4/6 drop with some 20inch coys or torque thrust. I just don't know what 84 with a 4/6 drop would look like with 20's so if someone has pics with a this setupor if there is any complications with running that big of a rim or if my long tube hedmans will hit speed bums with 20's being dropped that low. Also what is the best and cheapest method with a good ride to do this? I will see if I can post up some pics of what it currently looks like. Thanks.