Sorry but J5-CGU is crewed (all grayhairs!), they are just waiting for the authorities to release them because of some paperwork issues....
N88ZL does not belong to Lowa anymore, they changed to a BBJ2 a long time ago. I am not sur about the operators name but it is something like "Principal air services".
I was also a 707 freak when I was young but I now accepted the fact I would never fly one. The only place where you would have a chance would be by the Army.
Sorry for the bad news....