hm, i play Pantheon as a Damage carry. The funny thing is, my poppy build is pretty similiar to my Pantehon build.
On Panth i go:
boots (greaves later)
That is the core build. I upgrade the boots when i am at the well or i buy the sword first. it depends. also, infinity or bloodthirster first depends on the situtaion.
After these items, well i dunno. Frozen Mallet is an option. but it depends on what u need. more damage or armor versus dps carries.
But i think i would go for Starks instead of malady because its a bit stronger and the aura helps the team.
i dont like playin dps champs as tanks (i dont play poppy as a tank either) but i would build it a bit differently.
boots (ninya tabi or mercs)
ok, i'm not good with tank builds^^ but i think u should go for atmas as second item, because if u only have the health without a bit damage, the enemy team will just ignore u.