Saiga-12 is 1.5mm too. The bulged receiver (around the trunnion) is the main design difference in the V12 and S12 receivers. Saiga rifles had 1.0 thick receivers as well as most rifle varants..
OP, I haven't handled any of the JTS product yet, but it looks to have the same front handguard retainer width as an AKM. You should email me. I will send measurements of a couple of handguards and you can compare it with what you have to shed some light on your options.
evlutionz@yahoo.com