Help to identify crankset on Mercian

[keepitmencap]

I've just bought my first Mercian from ebay, and I'm very excited! However, I'm struggling to identify the crankset. The pictures are quite limited, but I can see that it says 'Strada 170' on the inside of the non-drive side. Initially I assumed Campagnolo, but they don't look exactly like any I can find online, and in addition they have some panto that appears to say 'AB'. Only thing I can think of is Ambrosio perhaps?

The bike is supposedly from 1984, some pics below. Any help greatly appreciated, thanks.

 

[torqueless]

Re:

Your guess is as good as mine regarding the pantograph, which could have been added by anybody, but the 'step' near the ends of the spider arms suggest that your crankset started out as a Gipiemme:
http://velobase.com/ViewComponent.aspx? ... AbsPos=132