I wasn't very happy with the 'wire loop around the socket lug' style of hold down shown above. Having an adjustment screw per lug made it difficult to get a good even mount.
I finally went with the classic style like
this one that BeCooling sells. When I get a free moment, I'll draw of picture how I constructed it, along with the version for center inlet blocks.
As for the blocks, you can't go wrong with the pin-grid blocks #rotor made famous.
#rotor's homepage.