It is not so much that I feel an urge to have the bike look like an original, it does not do that anyway, not by a long shot. The gearbox that I have at the moment is a bit troublesome with false neutrals and a very strange gearing. If there is a seal on the drive side it has long ago creased doing its job. As oil is leaking out quite heavily.
Anyways, thanks for the input. Now I know a bit more and I might, or might not move forward with building a gearbox.