Technical Need help to I.D this Valve cover breather

I have set of bigblock chev M/T valve covers made in Japan.
There is breather holes cut into the sides.
I am hoping one you hotrod part guru's may help me I.D what was there so I can get rid of the blanking plates. The approx size's as follows.( Converted from metric I live in New Zealand)
Bolt center is 4.33 inch
Hole is 3.7inch by 0.66 inch.

Thanks

 

Mooneyes, Stelling. Eelco, Cal Custom, Donovan, Offenhauser spring to mind. Here are a couple with similar 4" spacings and baffles. Seller has 2 x pair in individual sales. You could ask him for exact spacings and recheck yours.
http://www.ebay.com/itm/Pair-Vintag...Parts_Accessories&hash=item27e678bd46&vxp=mtr