Well I did get that hammer protection pad.
.....and I did have an old TM Hi-Capa bbu lying around, so I went about seeing if a different bbu could be installed on my Corolla.
To get the pad to seat on the slide, I had to drill out a little of the opening at the rear of the slide. Not all the way, just enough to get the pad seated flush.(the dents around the hole were previously caused by the hammer striking the rear of the slide)
Shown installed below
I had to slightly file the top of the TM bbu & make a notch for the rear sight. I also drilled a small hole so the rear sight could still be secured with its top screw.
The bottom of the bbu also needed some minor filing and sanding to get the slide to cycle without binding on the lower frame rails .
So can a different bbu be installed? Yes, but it requires a fair amount of work to get it working. Is it worth it? That depends on you.....for me it was just to see if it could be done.
(hmmm, maybe needs more cardboard spoilers
)