That's right, pam088 / 089/237/224/156 and other gmt in the bettarini case had movt. op.Vlll, for replicas we used 7750 with the gmt module. They are similar in all functions and characteristics.
Newer gen GMT models (PAM438 /441/320 and others) had in-house movements having GMT 12 hours, with p.9001.
Until a clone appeared, an existing 7750 was placed there, such as in rep 088, and the clock had an incorrect 24 hour hand gmt, which was not correct.
Later, VSF made a clone of p.9001 based on p.9000 and so everything fell into place and gmt in rep began to work normally in 12 hour format, and it became possible to put gmt's hand behind the hour's hand, hiding it. This VSF variant has been used up to now and in all new fashions since GMT.
The only thing is, the stars did not match for pam531 which gen had p.9003 with gmt in 24 hour format. While the old replica ZF or V6F (I don’t remember exactly, maybe both), had a 7750 GMT hand was 24 hours, and everything was correct. VSF later re-released 531 with clone p.9001, but it was already in 12 o'clock format, which spoiled the functionality, but behind the movt., It looked better with the correct position of the balance wheel.
This whole story is confusing people, and they are afraid of getting the wrong GMT hand. But if VSF did not put clone p.9001 inside 088, which is unlikely, besides, 7750 is indicated in the description, then in this case, there should be no problems. 7750 with gmt is not difficult. They are unlikely to do stupid things.