Dissipante 5u UMS heatsinks

I am planning on pulling the trigger on a dissipante 5u from the diyaudio store and was wondering what the UMS heatsinks are. Also how hard is it to drill the case for connectors? Is it worthwhile getting it custom drilled or can I do that with a basic drill press myself?
 
Oh wow OK now I get it. I found the document that has the hole specifications but it seems to be more optimized for 2 channel set ups with 1 channel per side. Since I'm making a 6 channel amp with 3 channels per side, and I was shooting for 3-4 pairs of push pull output stage, what is my best bet for which holes to use here? And the 400mm ums heatsinks would have 1 of these mounting hole sets on each side or two since there's two heats inks on each side?

https://cdn.shopify.com/s/files/1/1006/5046/files/universal-mounting-specification-v2.1.pdf