Can you suggest from where I could get an m62 LIM from as I might be able to retro fit the M90?

Sounds like a plan, which is something that have suggested to customers in the past. Best to contact:

http://www.moradpartscompany.com/ 

They manifolds can be found on some of these vehicles 1991–1995: Buick Park Avenue Ultra 1992–1995: Oldsmobile Eighty-Eight LS (opt), LSS (opt) Oldsmobile Ninety-Eight Regency Elite (opt), Touring Sedan Pontiac Bonneville SE with H4U RPO, not badged - SLE (opt. SC package), SSE (opt)