Suzuki 2 Strokes

Having acquired a rubber repro of the mod from the states i'm wondering whats the best way of securing it in place .
Can't see how this can make an oil tight seal just sitting on the casing..
A dab of Michel gasket cement perhaps ?

I just used case sealer on mine but don't know how well it works. I would think any kind of sealant that's compatible with oil would be okay.