Thank you for closing this gap! While it's not one of the early Deltas, it's still very nice to have the classic Jolly Club livery available for it :-)
I spotted two areas where I think it could be improved. Firstly, I'd move the driver/co-driver tabs on the sides of the car backwards so they're on the doors completely (as can be seen here
http://www.lanciarally037.com/team/jolly-05.jpg)
Secondly, the spoiler currently shows remnants of Lancia Martini lettering, likely in the specularity map? The older Deltas did not have spoilers, so its design is a matter of taste, but what about this:
https://i.pinimg.com/originals/9f/4c/22/9f4c2210b600336ce46cd220ba336c30.jpg