Sounds like a great find Jim, congratulations.
Not sure what 3 port brake you are looking at but you might want to consider one of Nathan's 5 port brakes. They are very high quality and very effective.
https://muzzlebrakesandmore.com/muzzle-brakes
JD338
The 64 gr BSB is a great choice. It was designed for a government agency to penetrate automobile door panels/ windshields and still take out a bad guy. They hold together even at 22-250 speeds.
https://forum.nosler.com/threads/224-64-gr-bsb.18868/
JD338