Im putting forest arches on a 4door Mk2.
In my case without crazy re enginerng of the door to still be able to use them I have to sacarifice some of the extra wheel well that you are ment to gain by fitting arches.
I have a feeling that Mk1 bubbles are WAY bigger than my lil archs. It will all depend on what you wants the looks of it or the extra room they provide. If you like the look of the huge wheels tucked right up under the arch I would say wait till you find a 2door cause doing it to a 4 will take a bit