What wheel and tire combo will you be running?
What kind of brakes, stock drum/drum, stock front disc/rear drum or something aftermarket?
The need for upgrading the front suspension with aftermarket tubular arms kind of depends on what the wheel/tire combo and braking system will be asking for.
Personally for my '64 LeMans convertible I am leaving the suspension all stock using rubber bushings, front brakes have been upgraded to factory 11" discs from '69 GP. I installed a 1-1/4" sway bar from a 2nd-gen T/A and 7/8" rear bar and factory boxed lower control arms. I also added a 1980 WS6 steering box, 3 turns lock to lock. I bought KYB gas shocks mostly because they were cheap, later on they might get swapped out for something a little less stiff. Will be running 14X6" steel wheels or swapping on some 14X6" Hurst wheels depending on the look I want, 215/70-14 tires. This is a pleasure cruiser, with upgraded factory braking and sway bars.
I totally went crazy on my '64 Tempest coupe with all aftermarket suspension, C6 Z06 brakes and 18X9" wheels. I wanted outstanding handling and braking, stopping well from high speeds was a priority. Details here:
http://forums.maxperformanceinc.com/...d.php?t=610357
My '64s both ride on the same basic frame/chassis as any other '64 -'67 A-body, so it has relevance here in the '66-'67 forums.
For a convertible I would say don't go crazy with suspension upgrades, these cars are very flexible and you don't want to overstress the body/frame structure. Going to urethane body to frame mounts would be a good idea to help stiffen and strengthen the car's body integrity. I would agree with the urethane bushings for the front control arms from a durability standpoint, will likely do the same to my car the next time around.