Just bought it - need advice on lowering and wheel sizes

[MACS69C10]

'69 Shortie with a 396, T400.

Lowering: Thinking 2/4. Suspension is all stock now. It has leaf springs in the back, so not sure where to find lower springs for the rear. For the front I am thinking tubular control arms and a heavier spring for the big block. Right now I am not happy with the ride. Great in a straight line...horrible on curves.

Wheels: 17 or 18 inch. Not sure about back spacing. Also not sure of best tire combo. I certainly want something taller than what is on there now...these are 215/70/15, 295/50/15...about 26.5 inches tall. Need to be around 29 I believe. I don't think I need all 4 tires the same...prefer a slightly wider tire in rear....same height or a tad taller.

Need advice! Thanks!