Thanks timbo for your answer, well done. This will help a fellow do a manifold conversion on his Peugeot where he needs to bolt up an adaptor plate, hence c/s bolts.
He also owns a road registered clubman with a supercharged rotary engine with obviously a fab power to weight ratio. The reason why a supercharger? Is that the s/charger gradually builds boost from low rpm and maxes out at 11psi at higher rpm, meaning the power delivery is gradual and doesn’t overwhelm the chassis & more importantly the rear tyre traction.
Volvo content is he has seen a Volvo site in Sweden selling the kooky M7 bolts but no one till now (prize to timbo) knew the said location to look for them locally.