I have two MKllls and each is in a double arm plinth. I believe you have room for two arms as well on that Porter Plinth. I use some high end arms and cartridges. The PC-1 Supreme on the 312s is very good. I currently also enjoy the Benz LP-s on Reed 3P. Albert sells a really good imported unipivot you may ask him about. I have a Shelter 90x on that one and even the Ortofon M20 fl super is great on it at $175. No experience with the Atlas unfortunately.
One of the spots I reserved for the EPA 500 system which is somewhat dated and not as fully functional as the others but sounds surprisingly good. It's also affordable and very flexible. I rotate armwands in about 30 seconds. It's a great way to work in less expensive MM cartridges(Ortofon M20 fl super, Empire 4000 D/lll, Shure V15vxmr) or a mono cartridge(XV-1s mono). They all sound great.
Anyway, you should be able to set this up with performance and flexibility that will push the limits of most budgets. Have fun.
One of the spots I reserved for the EPA 500 system which is somewhat dated and not as fully functional as the others but sounds surprisingly good. It's also affordable and very flexible. I rotate armwands in about 30 seconds. It's a great way to work in less expensive MM cartridges(Ortofon M20 fl super, Empire 4000 D/lll, Shure V15vxmr) or a mono cartridge(XV-1s mono). They all sound great.
Anyway, you should be able to set this up with performance and flexibility that will push the limits of most budgets. Have fun.