As far as i know, there are no WWII records at Fort Custer. If any records for the induction center are still in existance, they`d be buried somewhere in the National Archives in College Park, Maryland.
It`s probable that he wasnt at Ft Custer very long, not all men inducted there took basic training there. His age at the time, abt 27, and his civilian occupation, 'Semiskilled construction occupations' probably classified him to be assigned to an engineer unit, & was sent to anther training camp for basic.
I would suggest you send a request to the National Personel Records Center in St Louis, MO. for his military service record. See the research section of the forum for info on how to do it. Let me know if you need help with the form or anything else.