heater hose routing

OBTW, that upper rad hose needs to be corrected to get that kink out. Just cut an inch off at a time of the rad end 'til it lays in right. Being kinked will cause the rubber to crack prematurely, and not help flow.

Inertia, that heater hose to the water pump area looks like it is feeding to the low pressure inlet side of the pump, not from the pressure side. So the heater core is fed only from the very low pressure drop from the top to bottom of the rad, or so it looks to me; not much flow there.

As said, that hose now going to the rad normally comes from the pressurized area near the t'stat. There looks to be a temp sensor in that hole with the AC installation. Perhaps you can fab a Tee'd outlet from below the t'stat, to replace the nipple that feeds the bypass hose, that has 2 outlets: one for a shortened bypass hose, and a smaller one for that heat hose that is now going to the top tank of the rad.