The Andren program(Seamarks) will convert Loran number to GPS format. However you must know the offsets for your area for the conversion to be accurate.
I have the Seamarks program and used it to transfer all off my number from and old E120 Raymarine and Lowrance LCX.
It does have some odd quirks to it but it does work.
The owner of Seamarks is very helpful