I put a 2nd return spring inside the normal one, as the OEM spring has a pretty large diameter. I don't think I'm paranoid. When I bought the car, it had an Edelbrock on it that the previous owner had invented throttle linkage to fit. It would sometimes stick at WOT, and it was not the kind of driving excitement I look for in my cars. No passengers at the time ever asked for a second ride.
'65 Coupe, 302, Autolite 4100, C4, 2.80
'72 Grande, 351C, Motorcraft 2100, FMX, 2.75