MG Midget/Marina main cap

I have an A40 with a Richard Longman built 1275cc (Marina based) engine. Following a rather severe loss of oil pressure the engine has been stripped and it has been found that the centre main cap has cracked in half. Marina centre caps are in short supply, as indeed are 1.3 Marina engines generally. I have found a company that makes beefed up MG Midget centre caps but cannot establish if they will definitely fit.

I'm banking on you knowledgeable guys to tell me whether these MG Midget caps will fit or not

Thanks
Roger