It gives as much health as BOTH randuins and deadmans.
No, It gives as much health as randuins OR deadmans. All three give 500 HP.
And sense when is 85+ armor and 12% reduced auto attack damage from items considered "armor scraps"
I'm not counting the ninja tabbi, i'm talking about the chain vest and cloth armor.
If you keep RG and ninjas, and the base jungle item then the rest of your build gives
Cinderhulk + chain vest + cloth armor = 400 HP + 15% bonus HP + 55 armor --- all for 2725 gold
compared to Randuins which gives 500 HP + 60 armor + 10% reduced crits + 15% attack speed reduction + slowing active --- all for 2900 gold
Yi's damage comes from autos, and a 15% attack speed reduction steroid effectively reduces his total damage output by 15%!
Your build gives an extra 35HP but you lose 5 armor and don't have the AS slow. Randuins also gives you the slowing active to help chasing other targets in the game, and helps you against their Cait reducing her crit damage by 10%, because you don't have to just counterbuild Yi, the rest of their team matters too.
I'm not really going to argue with you about this too much further, i've given you the advice i can and its up to you to take it or not.
Also, you're losing your nexus towers leaving your thresh to defend 1v3 (i think from the minimap), what are you doing trying to 1v1 yi at your top inner turret?