Thanks! I think I'm close now, but unless I'm missing something, the clip
at the top appears to fit with the ends in the inner rim, and the bent
part (with the square that fits in the headlight slot) at the outer rim.
The other way (ends at the outer rim) doesn't line up right with the slot.

Also, it would seem that the reproduction seals I bought need to be trimmed
in length to properly fit the inner diameter of the trim ring.

In case I'm too lame to figure this out, do you think duct tape would
make a nice trim ring? wink