I don't think it will be a problem; it is just that it is not the normal avenue, so there needs to be some extra legwork done from your side.
As for the FOREX thing...that really wasn't a restrictive requirement even in the past, it was just a criteria for certain types of permits and as a check to ensure everything is legit; and then during the ban it was needed to file for an excemption for the ban.
You need to understand Sri Lankans to figure out why these are put in place. Lankans go crazy and become the most devious specimens on the face of the planet when it comes to cars.
If the checks were not there our people would be getting our neighbor's aunty's colleague's son-in-law living in Kenya to their long lost uncle who lived in London before passing away 15 years ago to their house-keeper's daughter now working in the middle east sending in cars. They would happily pay the expat Lankan's local relatives in Rs. thus impacting a huge part of the country's forex inflows. This also means there will be a bunch of people who would be shifting money back and forth in dubious ways (which by the way does borderline and sometimes is money laundering). Also, in the past this was also a part of motivating Lankan expats to save their USDs, GBP, JPY, etc in Lanka (there was a time where you would automatically get a permit for 20% of the forex remittances one makes, then at another time permits for government bonds purchased, etc...)
So as long as it is a legit case, it should be given due consideration; it is just that you will have to go knock on a few doors. Even the customs department is likely to say no at first because they don't want to open a new can of worms with a whole bunch of migrated Lankans wanting to send in cars bought from their foreign held money.