[Mg-t] Mk II Question

[wbeech at flash.net]

Dear List,
 
Have a friend that has just acquired a TD Mk II (7,500 miles).  The question
is that there is a bulge on the left-side bonnet with no reason for it in
the motor bay.  Cannot find any pictures or accessories that would explain
this need.
 
Also, are there readable numbers on the head to confirm that this is indeed
the higher performance MK II head?
 
Any thoughts are, of course, greatly appreciated.
 
All the best,
Bill