Joined: Feb 2008
Honestly, a rear sway bar won't do much for you. I had an on-axle one, and the most it did was beat up my exhaust. It sat about 2" above my axle and hit the exhaust every time I'd go over a speedbump or hit a crappy expansion joint on the freeway. Eventually it tore the hangars off the body, causing the exhaust to rest on the axle.
Your handling really won't be improved much with a rear sway bar either. The roll center with leaf springs is already high enough that the rear end doesn't need any more roll stiffness.
A 1 1/8" front bar will help, though. You'll be able to run closer to stock coil springs so you won't get beat up. But first and foremost, as baylensmanfl mentioned, shocks. The two best things you can do for handling on any car are good, quality tires and shocks. I'm a fan of Koni, as they are high-quality, tunable shocks, but there's getting to be more quality shocks out there. Varishock is another decent option, as is QA1. KYB is better than stock, but is pretty mediocre, honestly. Yes, a good set of shocks will run you upwards of $700+, but trust me, it's worth it!
Proud owner of a '65 289 coupe. Equipped with Edelbrock Performer intake, Quick Fuel 680HR carb, ported stock heads, 282 Magnum solid cam, Hedman longtube headers, MSD ignition, and decked and ported heads. T5 transmission with hydraulic clutch. Griggs Racing GR350 suspension. 8.8 rear end. Griggs front & Wilwood rear brakes. Many more mods to come!