No,
The requirements for an MPL are to be attached to an operator and do the MPL course on a specific type so you cannot convert to an MPL.
You can convert to a CPL and do an MCC (supposing you have ATPL theory) and apply for jobs in Europe.
Ps if you have 800 hrs you dont qualify to apply for airline jobs in FAA land as you must have 1500 hrs and most airlines want 3000 plus jet PIC time.