What I'm reading is rack and pinion is not recommended unless you do a full frame (like a Schwartz g-machine frame), and there's no reason for a tubular k-member unless you need clearance for headers.

So seems like leaf springs and stock k-member suspension is the way to go for a street car.

Last time I drove a '60s muscle car was a '69 big block Camaro, it felt like a pickup truck.