[justcobra]

Rmc is about the only cobra which is almost bullet proof and if you can source a series 3 which has the double stacker chassis it would be ideal.
Factory RMC from my understanding should have a chassis number stamped on the rails..
It was unfortunate that I have to construct a hybrid chassis when I bought my RMC project without a chassis but it is challenging.
$4k is very high for the engineering and torsional beam test and you have to work in gold mine to pay these exorbitant costs.
If you can Google torsionial beam test you can first hand what is needed in constructing the test procedure
I have sold a S3 Jag rear end to a cc forum member and I believe they are going to build a test rig to carry out that procedure.
I think that there is enough past information on this topic for your perusal on this forum.
Borrowing someone elses report would be helpful.