Chassis Discussion

Would love to see something geared toward Tube power amps. Heavier chassis to support 3 trannies and maybe a choke. Something along the lines of ARC style from years back (and you still see examples) with covers over the trannies but front half open with highly ventilated cover. Need something to support all the weight.
 
I'm getting ready to start the drilling and tapping the heat sinks on my Dissipante 5U 500mm chassis using the UMS hole pattern. I want to know what the recommendation is for placement of pattern between the top and bottom of the heat sink?