As southland has said it with your specs it will have to be custom and will cost a huge amount of wedge even if you do it yourself…
I also have built a triple MT-G2 and the heat issues are enormous if driven well. As a dive lamp should be fine, (mine wasn’t) but for extended use outside of water I will be going down the active cooling route if I ever get back to that project.
LinusHofmann is also doing a triple ’G2 have a read of that thread, well worth the time link
Relic38’s triple build, another good read link