MGB V8 conversion

[JohnV8#]

I recently became the owner of a 1972 MGB V8 conversion. The car is fitted with a Rover 3.5 V8 engine. I’m starting some maintenance work. First job is replacing the sump gasket to (hopefully) deal with an oil leak. Having drained the old oil I have realised I can’t find an oil filler! There are two breathers - one on the end of each rocker cover. When I am ready to replace the oil - is this done via one of the breathers? I will post a picture of the engine in the photo section. Any guidance welcome.