Re: Need Photos of F/W cooled Merc 260 engine W/ Rear mounted heat exchanger.
Would appear to be a kit from San Juan engineering - I've got the same one, but my hoses are generally much shorter & connect at the bottom center of the exhaust manifolds. I also see two temp senders - one at the outlet of the intake manifold, and the other near the raw exit of the HE. Could probably eliminate the latter, unless it's providing useful data for you. I'm attaching the only factory image I've found of the system - as my own is removed at this time for some upgrades.
You might consider going back to the stock height valve covers, unless you have some sweet roller rockers underneath those.

You may be able to eliminate the extra bracketry for the shift plate and ignition amplifier - check your elbows and see if you can mount directly (with the shorter valve covers).
Cleaning, sanding and painting does wonders for the Heat Exchanger.

