I've delved into the archives and here are the games where Boston have put six or more goals past Gainsborough Trinity.
Thu 4th Apr 1935 H L GAINSBOROUGH TRINITY W 7-1 Munnings(3), Bungay(3), o.g.
Sat 12th Dec 1936 H M GAINSBOROUGH TRINITY W 7-2 Munnings(3), Notley(3), Cliff
Sat 8th Feb 1958 H M GAINSBOROUGH TRINITY 4005 W 8-2 Hukin(2), Garvie, Andy Graver(3), Cresswell(2)
Sat 11th May 1963 A M Gainsborough Trinity W 6-1 C.Smith(3), Bull, Lister(2)
Wed 25th Mar 1964 H P GAINSBOROUGH TRINITY W 7-1 Bircham(2), M.Smith, Huss(3),Lensen
Sat 25th Oct 1986 H F GAINSBOROUGH TRINITY 1738 W 6-0 Hooks, Fee(2), Ward(2), Thomson
Sat 1st Jan 1994 H N GAINSBOROUGH TRINITY 1602 W 6-1 Grayson, Morrow(2), Munton(2), o.g.
Sat 1st Feb 2014 H N GAINSBOROUGH TRINITY 1255 W 6-0 Newsham(3), Miller, Semple, Garner