Personally can't see the point in splitting people up
I didn't PK RSC so I guess I wouldn't know, but I'm pretty sure pures PKed at/near the castle area. Which brings me back to the suggestion I posted recently, why not keep it that way and try and sort out some sort of a one way teleport from Edgeville to Graveyard or above to try and keep that authenticity going. 90s and flat's at Graveyard ++, lower builds in the castle area.
I also think it could be off putting for new players who are unaware of the area (if it were to happen) should they decide to take a walk up to castle to see what's going on only to see most likely no one. I think with some tweaks to the timer and hopefully a one way teleport to 20+ wild, we could keep up that authentic RSC PKing feel
Also who the hell ever goes to Varrock Border lol, it's very out the way and the best thing there is Rats..