Investigating possible Visa for work in China

I have now a job on hand for a Foreign Company to work on a 4 year contract at a Yard site in China .
The job is 12 weeks on site and 2 weeks travelling home or off work.

My Challenge is age. Being experienced and 63 years of age is no problem for work in Norway.. but I understand China has an age limit 24 - 65 years. Normally the line is drawn at 60 ??

If I enter a job in China and Apply for Visa to work there ...will it be granted (approved) if the Employer gives it letter to document that I work for a Company at a spesific work Site in China.

Is this a Challenge or is it possible for me..
Being very interested in Chinese culture and tradition and fascinated by the Country.. I really has an urge to learn more about China by working there.

regards
Einar