Planing for the future- suspension ?'s (70 Chevelle)

[tt69camaro]

I have decided to buy 18's and put 305/45's on the rear and 245/45's on front. I upgraded to bilstein shocks, front/rear sway bars and adjustable upper and lower rear control arms. I need to lower the car over these new wheels. What is the next step? This is NOT meant to be a corner carver, just a decent handling muscle car. Do the front control arms really need to changed to tubulars? Do I need drop spindles? What springs should i go with or should I just put coil overs on it? Thanks