I've seen Ikon, Progressive, and others, used with 130-150 lbs springs, on sidecar rigs. I have some, but they are longer than stock (a little bit) with 130 lb springs. You can have them for postage if you want them. Stock springs were between 112-118 lb., most aftermarket shocks were 120 lb springs. Avoid progressive springs, IMHO, they are a POOR match for this chassis. I HATE mine...still looking for a set of 110 lb springs for my new ORCA/Mulholland shocks (from 1980, but brand new).