I already have the 2 Acura from RSS moding that come out as IMSA DPi 21, there are also fellow skins from the Cadillac from S397 forum, that you could put them in a pack together with the Mazda from RSS, and thus complete the car list.
With respect to the Ferrari of S397 you have the skins made by a compi of the 2019, that you can take and put with the changes of the 2020 and you put it, something simple and fast.