My Research Says it is Operated by Principal Air
Owned by Lowa Ltd

I am not sure if this is the flight number, I think it might be the same as the tail number, but this is what I found
Ex reg. N5381X; D-ABUF with Lufthansa, Condor.
N88ZL (cn 18928/457)

Added this info In case you were interested or it helps with the paint
Current Registered Aircraft
Aircraft (FAA)
Manufacturer:      Boeing
Model:      707-330B    Search all Boeing 707-330B
Year built:      1965
Serial Number (C/N):      18928
Mode S Code:      53016706
Aircraft Type:      Fixed wing multi engine
Amateur-Built:      No
Number of Seats:      192
Number of Engines:      4
Engine Type:      Turbojet
Engine Manufacturer and Model:      P & W JT3D-3&3B
Owner (FAA)
Registration Type:      Corporation
Owner:      Lowa Ltd
Address:      Miami, FL 33166-2779
United States
Region:      Southern
Top
Status (FAA)
Certification Class:      Standard
Certification Issued:      1986-03-19
Air Worthiness Test:      2000-01-31
Last Action Taken:      2006-03-16
Current Status:      Valid

Thanks again for doing the paint
anthony