help required kiwi type engine

[frankclock]

Hello from Australia
I have just aquired a small engine it is complete, it has no markings on it but looks like a Westbury KIWI engine
This is a 15?cc air cooled single cylinder four stroke model boat engine
I have looked at pictures similar to it & see an oil feed to the lower part of the crankcase, my engine has a vented breather fitted into the same place
I would like to know how the oiler works as I have to make a fuel tank so I thought I would make an oil tank in a similar but smaller shape
I want to be sure oil is getting to the engine but do not want it to over oil
I am happy fixing my old vintage motorcycles but as this engine is new to me I want to be sure its not damaged
any advise will be helpfull or links to give me a better idea

thank you
FRANK DEAN
AUSTRALIA