Longchamp and Deauville with Pantera Chassis No.

No way. The numbers are different and chassis are totally different.

Early cars became a THPN number...

I have seen examples...

Than I stand corrected. When I worked there we had three different sets of vin punches. One for the Pantera where the first cupple of letters were welded together. The others were for Maserati and the longchamp/deauville/specialty.

Very rare car in the U.S. All the Longchamps listed in the original Registry start with THLC ('75-'85; production was '73-'86), so if there were other starting letters, they were likely mistakes that should have been caught by Italian state licensing before shipping.