His stun that attacks 2-3 times immediately says that it procs item effects. My question is will it proc it 2-3 times say with a bloodrazor or does it only proc it once? Thanks in advance.

it will proc 2-3 times.... Same with black cleaver.

depends on the item. shen/litch bane can only be proced every 2 sec.

I would only consider the Black Cleaver on him though, out of all the procing items.

Could possibly go with the others and build around that but i found its not as great as it sounds.

It's like you autoattacked two or three times in quick succession.
Renekton operates off AOE spells in a teamfight, using his Q and autoattacks to take down single targets. All his normal skills scale off AD pretty well, so AD items would bring more DPS than a Bloodrazor. Especially with Black Cleaver/Last Whisper - don't want to be dealing half magic damage when you're penetrating armor already.

Black Cleaver Frozen Mallet Tiamat, enjoy taking 2/3 of their hp in one furied W.