I'm also into Vintage motorcycles and we're quite lucky with repro decals.
A quick search has found it's a bit more patchy for MTBs or am I missing something ?
After some black Marin stickers if anyone can point me in the right direction ?
I tried Coraldraw and Inkscape but ended up finding a copy of illustrator.
It was much easier to use illustrator, I assumed I would find inkscape easy as
I use it most days for editing pdf, but a few things were just hard work.