I am surprised to be the first cynic to point out that most viewers barely know the difference between a 737 and a 747, which leads me to suggest that if you can't get a 707, you might consider a DC8 or a Convair 880/990 as they are visually similar enough to fool 90% of viewers. Whether or not you will find one airworthy is another question which I can't answer, but I do know that there were a couple of the Convairs parked up at Bisho for a few years. At least one of them was turned into a restaurant.