Trasmission Cooling Line Removal Help

Hi all
My radiator has a small leak. By small I mean barely leaks, but it bothers me enough and thought I would look to take to to a reputable shop to take a look at it.
Fluid needed to be flushed anyway. So I drained the radiator, disconnected the hoses and set out to do the trans lines. However I am stumbling with them. Cant really get them to "loosen" up. Appear to be copper line with brass fittings, so I dont want to put too much elbow grease to them and break something, creating even a bigger problem.
Do not know the last time these would ever have been removed. 1972 scamp that is mostly all original. I hit them with WD40 to let them soak.
Advice? Thought this would be easier than it is but maybe I am missing something? I am thinking this is a flare nut but theres not enough room to slip a flare wrench on there and I dont want to "round" off what is currently in place.

Also next year the 318 is coming out and getting replaced with a 360 and more than likely a new radiator anyway. Should I even worry about getting this one fixed? As mentioned the leak is TINY. Part of me says just change the fluid and enjoy it this summer and get a new rad in next winter.

Thoughts?

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Try PB Blaster instead of WD40. I'd use a small vice grips and a flare wrench. It should come apart.