I currently have a 12 bolt rear mounted to my monoleaf suspension. I never removed the multileaf mounting perch from the 12 bolt, so in order to compensate for the mono - to mutli difference in height (leaf thickness), I inserted a block of steel on the top of each leaf spring (between the leaf spring and the rear end), which allows me to still use mono leaf shocks. I never had any problem, but just curious about the safety, and if I should have mounted the block under the leaf spring (between the leaf spring and the lower shock mounting plate) and used multileaf shocks, which are longer than mono leaf shocks.

 

you essentially have a set of lowering blocks installed... I would not consider it a safety issue, but it may be a traction issue. The more space between the rear end and the leaf springs, the more leverage the rear has to twist under hard acceleration. So it could cause more spring wrap, and possibly increase/worsen wheel hop.

many people have lowered their cars that way, just not racers....