Need tire/wheel and lowering ideas

[NevadaDVX]

I am building a 71 longbed for a lady that will be semi-custom. I've done a smooth gate, roll pan, Firebird markers, billet grill, billet tails etc. She wants it lowered a bit, but not on the ground, mainly to fill the wheelwells and still be a good comfortable ride.
Do you guys have any suggestions on how much to lower it and keep it streetable, and what size tires and wheels? Not interested in bagging it or anything crazy like that, just simple spindles/springs. I really doubt she will want to go much over 18" rims. Pics would be great! I'm a bodyman by trade and don't get into this custom stuff much.