Welcome to the forum. I use the Z-Axis 6 weight switch as my tight quarters Spey rod.
Here are some pieces of reading:
Speycast: The world of Spey Casting - Skagit Fly Lines by EF
As for line setup, you need to figure out which styles that you wish to throw. The choice of casting will depend on the flies that you will throw. Will you throw heavier flies or sparse classical styles?
If you choose to go cast mostly heavier flies, cast a Skagit style shooting head like the Rio Skagit Short
. The recommended weight is the 325 and the 375 grain sizes. If you want to have your rod bend more towards the mid section, get the 325 grain size. If you want it to load further down, go with the 375 grain. For multi-tip setup, purchase the Rio Skagit MOW Tips (light size)
. This tip selection will allow you to play the depth game. Add short leaders to the tips, and you are in business.
If you choose to cast sparse classical style flies, I would choose the Rio AFS
floating shooting head. This is a Scandinavian style shooting head. Choose the 4/5 (300 grain) if you like to cast off the tip, or chose the 5/6 (340 grain) if you want to cast more towards the midsection. To play the multi-tip game, get a selection of 10 foot Rio Spey Versileaders
. Just tie some tippet to the end of the Versileader.
Both are shooting heads, so you would need a shooting line. Since you want to purchase Rio products, get either a .024" or .030" floating Powerflex Shooting Line
. The thinner diameter will pass through your guides easier. The thicker one is easier to handle.
My line setup for my 6 weight Z-Axis Switch is the 325 grain Skagit Short head. I have not tried the MOW Tips yet even though I have the kit in my gear bag. I do not throw large Intruder style flies on the switch. I throw mostly buggers and leeches.
If you are going to throw some heavier flies like the large Intruder styles, I would err towards the 375 grain head. You will be able to get more load to deliver those flies.