1959 A10 GF Sludge Plugs

[Keith R]

Hello,

I am hoping someone may be able to help.  I have acquired two new sludge plugs for the above however each one is different. 
One has a flat back and the other has a domed back.  Can you advise which side of the crankshaft each should go?

From what I can gather the one with the dome should be on the LHS, but wanted to get the expert's advice first before fitting.

Thanks in advance

[Wakeman]

Here is a sketch I made when rebuilding an engine. That engine has long since been rebuilt and runs great

[Wakeman]

Here's another sketch I made back in 1992. It corresponds with the first sketch I sent

[Keith R]

Thanks very much Wakeman.