Ok, so here is an update.
Test fitted the adapter plate, marked the front bearing retainer on the transmission, and cut the bearing slide.
Then tapped the roll pin out and swapped in the new -4 adapter.
Fits perfect now. Also notched out the bell housing for the new lines.
Mounted the flywheel, clutch disk (7M-GTE), and pressure plate (3S-GTE).
Mounting the trans was a pain, since the W58 was so small and light I could wrestle it in in just a minute or two. The R154 is such a beast I had to use my small BFH to give a little more room in the trans tunnel. Next time the trans come out (hopefully not for a long while) I'm going to hit some of the high points on the ribs of the bell housing with the dremel. That will make installation much easier.
The exhaust fit other than the driver side touched the R154 trans cross member. I tapped the pipe and cross member and that worked out nice.
I have about 60 miles on it now, can't wait to break in the clutch so I can dig into it.