Inlet manifold blanking

[JKaiDekA]

Hey guys! Going to do the catch can/pcv delete mod this week. Was planning to do it anyway but have noticed the pipe connecting to my bottom breather 90 degree bend has completely broken off!!!

Anyway my question is this...
I have the two nipples on the bottom of my inlet manifold that need blanking off. Was going to use these:

http://www.autosiliconehoses.com/silicone-hose-end-caps-2-pack-blanking-plug-bung-4mm-to-32mm.html

What size do I need? Didn't want to go pulling them off just to measure them as I'm still driving it (all be it without a lot of boost!!)

Also, this is the catch can I'm getting, is this alright do you think?

http://www.ebay.co.uk/itm/0-5L-0-5-LITRE-BRUSHED-ALUMINIUM-OIL-BREATHER-TANK-CATCH-CAN-WITH-19mm-3-4-BARB-/301352973745?pt=LH_DefaultDomain_3&hash=item462a0975b1

One other thing, while Im at it, would you advice sorting out N249 mod while I have the cover off?
Cheers guys!
J