You very well might be able to get the real thing if you make some phone calls. I assume you are looking at renting. Moving lights will do this, but they will need some help from some
haze. However, there are plenty of people out there that will bring a WWII era searchlight out to your
theatre. Many people collect and
restore these gems. Some companies cost an arm and a
leg to come out and lamp up their light, others are just collectors who look for excuses to lamp them up and will do so for just the cost of operation. Might be worth it to look around and see if anyone owns one or two.
However, if thats not an option, there is always something like the showgun. They are made to do exactly that. You could also look into getting a
Syncro or two. They are made to do this as well. Some of their older models can rent pretty cheap.
All of this being said though, both the options I listed are extremely
power hungry, so make sure you have that available.