Yes I measured up my 260 2-seat for you and posted it but the post has since disappeared.
I'm away from where my car is at present so can't immediately re-measure, but IIRC I measured 1210mm the exposed length of the centre section between the (over-lapping) end caps same as you have, & I measured along the leading (front) edge closest to the car. Take that measurement as approx because there is some built-in tolerance in the bolt holes where the sections join together. I can confirm that dimension later.
Also, the end cap fixing brackets which bolt to the side of the body are different to the one in your photos, being right angled to accept a single bolt passing through from inside the rear guard.
From your photos I think you have a 2+2 bumper there? In any case offer it up to your car and you will soon see!
Edited by gilltech, 19 May 2017 - 12:20 PM.