The 7th Infantry Division did indeed serve in the Pacific, checking on attachements to the division I find only one permanent engineer regiment, that being the 13th Combat Engineers. I found two unit associations, one for the WW@ area and one for the Korean area, they are both enclosed.
13th Combat Engineers Mr. Maurice H. Reeves 7303 "H" Street Little Rock, AR 72205-2636 (501) 663-4622
13th Engineer (C) Battalion Association (Korea) Mr. Levi O. Haire 6078 Danbury Court Morrow, GA 30260 (404) 366-9891
Hope this gives you a start in the right direction.