212k with original fluid, in a little bit of a conundrum. I believe the cause of the problem is the faulty pressure regulator leading to a spun oil pump bearing, increasing play in the torque converter causing that dreaded "chugging" sound. I also read it could be that the torque converter is not engaging(disengaging) fully and thus internally grinding, however I have less evidence that this is the case.

The three flex plate bolts previously came loose and were removed, cleaned and re-torqued with threadlock. They're still tight

There was a post from a few years back along with a Youtube video which captures the exact sound coming from my box.
https://www.youtube.com/watch?v=utUQk2atBBM
http://www.maxbimmer.com/forums/showthread.php?t=146640

Someone in that forum post recommended putting Lucas in the trans and driving it until it blows. I'm wondering if this is a viable short-term solution compared to just dropping the pan, inspecting pressure regulator bore/upgrading pressure regulator, changing the filter and replacing lost fluid. I realize opening the box this late in it's life is quite a gamble so I want to take the least destructive path of potentially prolonging the life of this trans/TC.

Any help will be appreciated