I stand corrected about the TT132 struts, my apologies.
My experience is with the RT132 struts into an RA23.
I have heard of a few people who have found problems fitting
Corona struts to a TA23, but I'm glad at least one TA23 owner found it was fuss free.
As for why the Hilux caliper upgrade and not just run the Corona two spots, no real reason. Plenty of people have upgraded their RA23/28 to just the Corona struts with the standard brakes. Nothing wrong with that.
It was because the Corona stuts were built up off the car, I went all the way with the conversion in one hit, and added the Hilux calipers.
BTW, a have a pair of RT132 twin pot calipers for sale now. Best offer.
Cheers,
Mitch.