The M40 was never sold in the USA actually. Sort of like how BMW has not had a 4-cylinder model for sale here since the year 1999, although BMW might be selling the new turbocharged 4's here now.
There should not be too much trouble finding someone with M42 mount arms for sale. Shipping to Singapore may be a little expensive, but it may be the best option. An alternative to the M42 mounts is the mount from an E28 535iS with the M30B35 engine. I ran those for many years because they cost a lot less than the hydraulic M42 mounts. They do cause a LOT more vibration though, and I eventually went back to using the proper M42 mounts.