Having spent an hour the other day swapping freehub bodies between 3 different 7 speed Shimano hubs I can assure you that whilst they feel like they might all be interchangeable, they ain't.
Without having any other hubs/bodies to try, this is also the impression I get from internetting.
Although as mentioned, I think the freehub off a Shimano 600 FH-6401 would fit the FH-1055. I suspect the only differences are the number of pawls (three on the 600, two on the 1055), and the colour.
Having spent an hour the other day swapping freehub bodies between 3 different 7 speed Shimano hubs I can assure you that whilst they feel like they might all be interchangeable, they ain't.