Questions about lowering

I have a few question requarding lowering my truck further, it is a 2001 ford ranger sport/edge 2wd.
It has torsion bars with 3" drop keys, but rides terribly, the rear has the djm 5" drop kit minus the 3" spacer.
Currently I have lift shackles on the back due to my front being so much taller.
I have question requarding whether or not the djm 4" coil spring drop kit could be used
Without many modifications, and what modifications will be needed. Also,
I currently have 17x8" bullit style wheels with 245/65r17, wondering if there
Is a better tire size to use, but I do not want to loose my factory flares but
I am willing to trim them out if necessary. Thankyou for all your help