Personally, I'd go with 2x stam/wis and 4x stam/def if you don't want to use any stam/hp stats since you get a plenty of wisdom from your healer gear for priest.
Yes, you could play in siege with that build, though you won't have nearly as much hp. Even if you went 1/2/3 stam/wis/hp/def, I would still recommend building honor gear if possible because of the damage reduction from it. It will make you a lot tankier in pvp, but I understand the want of not spending a ton off money, but if you're playing in the upper end of siege, you will probably want pvp gear.
Reni
Mithras
Zerienga - 90/90 P/K
Téster - 95/61/60/45/45 CH/WL/R/P/M
Dontkillimascout - 90/61 WL/P
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