You guys ask the BEST questions!
I did a little music box movement research this morning, here are my findings:
It seems music box movements have become quite "standard" such that it looks like "Most" will bolt right in to the base of the kit Ferris wheel bolt pattern.
The industry standard is: runs "up to" 3 minutes on a full wind...mine went 2 minutes and 21 seconds....so the "cheater" method is to slip the drive band off the movement and just run a longer drive band from engine to Ferris wheel axle pulley, then wind the un-belted movement and fire up the engine.
This has Several flaws, by the time you get your belt tracking/tension in its happy place...you may have Less than a minute of music left!
Also, it just would not "look" right to have a longish belt running way up to the big wheel axle on perhaps a 45 degree angle.
So that brings us to Bruce's thoughts that is would be cool to have the engine drive the music box as well!
The big wheel has a smooth metal pin for axle, so I feel it will draw not much for power at the slow scale speed.
So that brings us to the music movement it self.
The unit that comes with the kit is on the lower end for music movements, it has a metal base and drum, which IS good, but the gearbox is mostly plastic gears. The ONE redeeming quality of the kit movement is it's fitted with the metal pulley all ready. I think it may be possible to remove All the plastic gearbox parts And the rather stout watch spring winding spring and this will leave us with a mostly metal unit that turns quite freely with a pulley drive!
Few side notes:
There is a tiny "bakers fan" right in the gearbox!...I believe it's function is to smooth out the speed that the spring loaded gearbox gives up its power, much the same way we belt up our steamers to a baker fan to keep them from racing
The baker fan axle is mounted vertical rather than horizontal, if you buy one and are looking for the fan.
So now we have the "extra" parts gone (hopefully with zero damage) the next thing to consider is speed.
I put a tiny mark on the movement belt pulley at TDC and wound her up, it takes 15 seconds to make 1 complete turn so the Drum with the pins on it must run 4 RPM
I predict if we get slower than 3 RPM we will be in lullaby territory and faster than 6 RPM may sound like Salsa.
I have achieved close to these speeds with a double reduction....you heavy hitters may have a transmission in stock to do the job?