Hey mate, I was doing some research on this quiet a while ago.
From what I read, general consensus is not too close to the TB, and not too close to the bellmouths. I have mine towards the 3/4 cyl in the middle, facing down (looks much cleaner).
Not too worried about oil making its way in as my PCV doesn't recirculate back to the intake, however in future I may recirculate it back and just keep an eye on the hose.
Worst case scenario is oil ruining the MAP, otherwise just route your vacuum hose higher than the nipple along the top of the firewall (factory 7/9 location).
P.S, that is a sweet looking manifold, one for a 16v would be awesome.