When you say it's never getting up to temperature, is that in the sense of never reaching the midpoint on the gauge?
That middle point might be an arbitrary reading so not a worry if it doesn't get there. Maybe 1/3 is right where you want it. Especially if the stock Pinz tstat is an 80C unit. That is certainly what I would want to run in a Pinz where the engine works hard all the time. I wouldn't want the 87C version in there. You really need the extra time and heat capacity margin the cooler tstat gives you to keep temps from running away from you when you pin the throttle climbing a big hill on a hot day.
Here where I live in Montana USA, I run the 80C thermostat year round, including in the winter where temps are routinely -25F or lower. The engine makes enough heat to keep the cabin warm regardless, and fuel economy is not affected by the lower operating temp. There are no downsides from what we can tell, provided of course you have a good multigrade synthetic oil in the crankcase. As ngoma said, the tstat will regulate temp of the coolant regardless of what the fan is doing.
The big challenge with these engines is keeping them cool enough when they are working hard. I wouldn't worry about it being a little "too cool".
I owned a truck where the temp gauge happened to be calibrated with the normal operating temp region occurring where the needle was more than halfway up, like 3/4. At first it was extremely unsettling to look at the dash while going down the road and always seeing the temp gauge needle sitting above the halfway mark. It put my nerves on edge. My first instinct whenever I saw that gauge reading would always be to immediately start downshifting and looking for a way to dive for the side of the road!! BUT that was the correct place for it, on that gauge -- confirmed with a scan tool. What I'm saying is, we're programmed mentally to want to look down and see that needle locked in on rock solid dead straight middle. But 1/3 up the gauge sounds like very likely where yours should stay, given that you have a confirmed functioning VDO gauge, new high performance cooling system, and new tstat.
