So it's not holding a vacuum? Leak indicated, but, this has always been a grey area as I notice refrigerant that's dissolved in the oil change the vacuum reading after I shut the pump off. When in doubt vacuum it longer. What's an hour to you vs. the "in a hurry shop" that does only 15 min. I am used to GM systems that use a pressure switch. Dodge RAM systems use a temp probe. The difference being when running low on refrigerant the low side on Dodge RAM can be in a vacuum and any leaks will allow moisture in the system. You could be boiling moisture out of the system with the vacuum pump and that takes time.
Evaporator leaks were said to be common. Hard to find. The sniffer goes in the condensate drain after sitting in a closed garage windows down. R134a is heavier than air. The blower dilutes all but massive leaks in the vents to a sniffer. Sometimes you can see dye in the drain. I would pull the compressor clutch off and inspect the shaft seal for oil to help verify you found the leak.
Generally a A/C leak will have an oil stain around it. The charging valves are famous for leaking esp. after service. I automatically replace both every single time I touch an A/C system.
Trade the ECT for FAN-PWM % on your display. (The temp gauge on the dash if it moves: back out of the throttle.) Is the ECM calling for 100% PWM on the fan trying to get the damn thing up to speed from A/C high side pressure? That info will tell you. I set the box to alarm at 400psig and immediately would cut the HVAC blower speed down.
How old is your fan clutch? IMO the RPM around 300 indicates an old clutch that is going to take a long time to lock in and get up to speed.
Generally on startup one wants the highest fan speed setting. Interior is hot, you are hot, it's hot out... However if the engine fan isn't over 1K RPM at idle or below ~45 MPH you are going to watch the A/C high side spike over 400 psig. Start the fan speed on a lower setting until the PWM on the fan is less than a solid 100% or the fan is spinning over 1K RPM at idle. Recall the fan pulley is smaller than the crank pulley so the fan can spin faster than the engine RPM. The PWM on my 2003 was either 100% or 0% and when it reached the desired fan RPM it would start changing from 100 to 0 then 100% again. (I recall: No 40% etc. just reads like on/off.)
I would use a new MOPAR condenser and have it coated. Expensive but worth it.
https://www.turbodieselregister.com...thermal-dispersant-on-an-ac-condenser.264486/