SB Cam Thrust Plate P5249637 no longer made? Only tensioner now?

Yes... as someone famously said on this site "No cares as much about your [stuff] as you do." And I'll add: "It's less complicated when you screw up yourself".
All very true. My local machinist who did the line hone on my block
Did not get the size to my satisfaction(too big) he was not happy when during the mockup I discovered the bearing clearances were too loose. I brought the block back to have him do it again and he gave me some grief.
I said too him, would you not rather me bring it back now and fix it rather than me come back here after a bearing failure and fight about who,s fault it is. He redid it, I assembled it and now it's on me.