Redemption or knights vow on J4 top?

I've been entertaining the idea of trying either of these out on J4 top. Not sure which would work better and/or when to build them.

Redemption: the active synergizes really well with his ultimate - if an immobile doesn't use flash I'll be nuking them for 10% max health AND healing myself. I also have been running some mana Regen in masteries over executioner (3 and 2 split) and could go back to damage with the mana Regen from this item. J4 also has a shield to make use of the passive, and i try to hit 45% cdr which this giving 10% on top of 20% from tf/cleaver and 10% scaling cdr runes would work out. Obviously I'm still rushing black cleaver against a tanky team and trinity force against a squishy team, but when would i build this? I think second would make it great for Lane sustain and early duels, but I'd give up too much early tankiness. As a fifth item after cleaver/boots /dead man's/titanic seems reasonable?

Knight's vow : Seems like an awesome choice if i have a fed ally to generate massive healing for me. It unfortunately seems to go counter to my normal hp-stacking titanic build (as resistances would scale better with the healing) but it could still work. The idea is that despite being the tank I'm often focused hard when i dive the back line - so i won't take extra damage from the transfer but will get healed. If i do take damage then I'm helping the carry. I think I'd need more stats before building this - so fifth like above or even sixth with another defensive item (GA, banshees, randuins, etc..?). However I'd be short 10% CDR here unless i went warmogs or got blue buff (i do tend to steal blue buff a decent amount to be fair).

Any thoughts? May either of these work well on J4?