I have a 27 cm housing if interested.
The HT3B I have came off of a 400 Big Cam Cummins. The turbine wheel is a 100mmx96mm, IIRC. 76mm is too small for the turbine wheel on an HT3B. And I don't believe a compressor wheel was made to be 76mm. I believe the biggest compressor wheel Holset made for the HT3B was 74mm.