Exhaust threaded into aluminum manifold

[Gripper]

There is a great discussion of MBowswwer's similar problem here:


https://www.cruisersforum.com/forums...ld-281296.html


My issue is a little different. Also a Westerbeke aluminum manifold (circa '78 W30) but there appears to be a cast or black steel female boss cast into the manifold, see the attached photo. I'm trying to figure out whether to try to PB Blast and heat and try to turn the male nipple out of this without destoying the aluminum manifold. And if that's successful, what to replace the exhaust plumbing with. I'm guessing black steel, since I'm guessing this setup has lasted for 46+ years and if it's going into the saved steel/iron boss in the manifold it's not introducing any new corrosion issues from disparate metals.


https://1drv.ms/i/s!Ar218psktI-8hJ8_...mPtCg?e=BdRszR