Vorph
Silver Baronet of the Realm
Darkmoon Faire (starts Monday) can upgrade them still. It costs 44-64 tickets per heirloom, and you can get something like 155 tickets per faire if you're starting at 0.
As for the Garrosh weapon, it caps out at 620 and won't be replaced until you get a heroic or crafted ilvl 630 weapon at 100. Crafted ones are rare rather than epic which makes them a waste of truesteel that could be used to make epic armor instead, so it really comes down to how lucky you are in heroics. It took me for-fucking-ever to actually get a heroic weapon in MoP so I fully expect to be using the heirloom for a couple weeks.
As for the Garrosh weapon, it caps out at 620 and won't be replaced until you get a heroic or crafted ilvl 630 weapon at 100. Crafted ones are rare rather than epic which makes them a waste of truesteel that could be used to make epic armor instead, so it really comes down to how lucky you are in heroics. It took me for-fucking-ever to actually get a heroic weapon in MoP so I fully expect to be using the heirloom for a couple weeks.