ZL-1 coil spring rate + addl. options 4 A Z-11

[Paul S.]

Hi Everyone,

I'm working on a restomod 69 BB Z-11 Pace Car. I'm installing an engine much like an all aluminum Zl-1. My question is what would be the correct front coil spring or coil spring rate to use on a convertible with this type of engine, vintage air conditioning, stainless steel headers, aluminum pulleys and aluminum radiator. The car has power steering and the standard equipment that came with the Pace Cars such as cowl hood, hideaway headlights. It's a four-speed car.
I would like a front end that rides high and will not slouch over the years, but will give a bit when needed. I've bent some headers from bottoming out in the past. I understand the ride may be a bit harsher with a heavier spring, but I'm used to it.
I ran heavy duty springs that were meant for a cast iron big-block, air conditioned car with copper/brass radiator, but instead went with aluminum heads and never installed any of the engine compartment a/c components and i went with an aluminum radiator. The springs never sagged and I loved it, but there were still a few times I bottomed out.
What would you guys recommend and from where would you recommend I purchase a quality pair from. Thanks for any help, Paul