Old dowels often in need of grinding off dirt and marks, grit 400 paper. If oval shape, replace it. I ordered several dovels years ago.
This dovel same size as under cam towers.
Cover hole can have marks so dovel will not fit.
Aftermarket gasket usually fit bad.
Some holes need to be widened
with a sharp knife since hole pattern is wrong.
Here a cover to a CB750 K6
2 dowels.