I believe 1G dual piston calipers used the 3KGT style fitting - it has a screw in brake line as opposed to the banjo bolt. If you have that style caliper the banjo bolt I believe could be the right pitch but perform in the manner you are describing as the thread-in brake line was not nearly as deep as the female hole for the banjo bolt.

I have run across inconsistencies between the years so it is not all-inclusive.

When looking into the hole on the caliper, is it straight thread or tapered (pipe thread looking)?