I understand the springs go on top of the radiator mounting bracket. When they're between crossmember and rad bracket the rad sits too high. I've had very good luck running 1/2" Neoprene pads on my 32. No problems in 40,000 miles. The pads are snugged up with a stainless 3/8-NC bolt, appropriate flat washers and a nylock nut. The nylock is spun down to where all the play is out and that's it. It doesn't loosen.
I run super super light springs to mount the radiator. I have a lot of twist in the roadster frame and when I mounted it with those heavy springs it tore the radiator apart. the radiator steady rods are triangulated so the radiator has to move with the firewall. Any twist and it's good by radiator.I have some springs about an inch long and can be compressed with a load of maybe a quarter of a pound!. It has worked for me for 14 years and a terrible bunch of miles. Never damaged another radiator. I use 3/8 bolts and nylok nuts.