Oil line on a six, hose and valve installed! Options

[fixer34]

Bought one of the Rothsport oil valves because I was tired of cleaning up oil after taking the car out. Installing it was my weekend project (what did you do to your 914...?) Had the pull the heat exchanger, and the hose connection at the oil cooler came off surprisingly easy. The connection at the U bracket is another story. It hasn't been loosened in at least 30 years and having no luck breaking it loose. Any suggestions?

And before you ask 'how did I change the oil?'; the car has been driven less than 10k miles in the last 30 years, and 'oil changes' were done almost on a continuous basis by refilling since the leakback was so bad anytime I drove it. New lower valve covers & gaskets helped, but it still drained about half the tank when it sat for several months.