I'd fit the electric water pump and use the gilmer for the alt, just have 2 get a smaller belt. With my old TD with a healthy 302w I ran a moroso 12v motor then changed to a Davies Craig EWP (at that time they only had the 80L/min) and modified the std water pump, alloy radiator and 16" fan, ran ok but still got hot. Now Davies Craig make a 110L/min
i'll be using one of these with my new 393 single turbo TC Cortina project but I think grouting the block will help me the most. Well with water temp anyhow oil temp will come up though
but easy fixed.
All the best. It's a true pain in the ass when they don't run at a nice temp