The early 4JT TZ125 rear disc has a 4DP prefix, and the last of the 4JT's has a 4TW prefix. All the same three hole mounting. TZ125 rear wheels have the same disc brake mounting even between the three and four hole sprocket mounting differences.
A quick measurement gives me a bit over 7-1/4"...which jives with the service manual's statement of 185mm.
I think Honda RS125/NSR250 rear discs are also 185-186mm. I wonder if they all have the same three hole bolt diameter.