Just keep in mind im going from memory with this. And that's from a private server i used to play on (i never played on retail after TBC). So i can't know for sure it's 100% Blizzlike.
But anyway, left vendor (dwarf) should have the 403 ilvl items and the right one (Dranaei) the 410 ilvl weapons. I don't think the right one is missing anything but for some reason she has the boots that the left vendor also has anyway. I don't think they need to be there. Also, i have no idea who should sell the 390 ilvl stuff.
So like you say, the Hpala set is missing from the left vendor. I don't know about other classes though, i assume the only armor items that appear are the ones that your class can use, correct? You can see all the weapons though... Eh, that's why i'm not sure what you see or not in the retail.
Anyway, the 403 ilvl DPS set is there so here are the itemids for the 403 ilvl healer set that are missing:
73561
73565
73563
73627
73626
73625
73621
73622
73621
73628
73629
73639
73558
73556
73560
73559
73557
I also noticed he is missing all the relic/sigil stuff from both hpala and retri. So i'm not sure if he is the correct vendor who should sell those. But here are the itemids anyway:
73490
73624
73594
73642
Again, that's what i remember from Warmane server, not retail. So i can't tell if it's blizzlike.