Old engine into new car

A colleague has just fitted a 1.9litre turbo petrol engine from a 1987 Pug 405 Mi16 (the rally car spec engine) into a later 206 to make a replica 206WRC

It's an 87 engine so we can test to non cat limits, but we also have an RfR for A catalytic converter or particulate filter missing where one was fitted as standard

Which takes precedence? Can we pass because it's an earlier engine, or do we fail for a missing Cat?

Submitted by phaetonott