Yes and no is the simple answer.
I got a set off e-bay that was a mixture of ATP Decal, their sheet was for all Pan Am wide body inc L-1011-500, DC10-10, DC10-30 though more importantly the 747-121 and 747-SP21. Though this sheet wasn't complete and had a "Billboard" SP scheme included from another company, I've yet to find out who's sheet it is as mine are only enough to do the job.
I take it you don't have the Welsh Models vac as you wouldn't be asking this question. Then it must be the Sasquatch conversion, I have one and looks an, errm, interesting build!
If you hang fire for a while, Two-Six might be doing a new set of SP decals possibly with the Flight 50 decal. There might also be a Pan Am Cargo 747 sheet released too *fingers crossed*
Your SP also depends on what livery you want to do. I guess getting a sheet of 747 windows, I missed a set on e-bay last week
and using a billboard decal sheet might do, cutting the windows to length for the SP but then you don't have the sexy decal saying "Boeing 747sp" which is after all a really nice touch on Boeing aircraft.
PM me from time to time and I'll let you know what I have in my spares.
Hope this helps of sorts but really it's just a case of hoping a set comes up or Two-Six do a sheet or you never know Welsh might re-release their SP then just ask to pay for the decs seperately. If they won't get their SP and find another scheme for your original
