I think all model A rain gutters are the same and the support arm holes are the same. The trunk lids are the same size and only the latch area it different between 28/29 and 30/31 lids. There is a metal reinforcing plate used on original rain gutters to make the pivot bolt anchor better, otherwise the weight of the lid might tend to bend the gutter. I can take a picture of the reinforcing plate if you want one. Tomorrow I will try to measure the distance from the upper part of the gutter to the center of the support hole. I would need your email address if you want a picture of the plate on the gutter
Rusty Nelson