I don't have any pictures of the copper, but what I mean is similar to
this which is for sale on UK eBay.
You need to measure the gap between the bottom of the heatsink and metal top of the chip and buy the right thickness of copper sheet.
Then cut out a piece which is the same size as heatsink.
Then use
Arctic Silver Adhesive (UK eBay again) to glue the copper piece to the heatsink.
Put a very thin layer of
Arctic Silver heatsink compound on the underside of the copper piece and on top of the CPU, and fit the heatsink to the motherboard in the normal way.
Use the thinnest of thin layers of AS since it's used to fill in any imperfections between the metal layers. Too much could stop heat transmission from the chips to the heatsink.
Alternatively (and maybe not the best solution) is to buy some
plastic thermal pad, which is slightly thicker than the gap, like this on UK eBay. (Type "thermal pad" into eBay search.)
Hope that helps!