Someone on FB has done a very nice job in 1/48th of a B17 with motors & LED's.
I'm doing likewise, with a Revell issue B17F, (just because I like to make things interesting ), but my modelling room is in transit, so not much progress at the moment.
I used approx 1cm diameter motors I already had, which fit snugly in the back of the engine plate, (with a corresponding hole drilled in the firewall). They just cleared the undercarriage plate on the inboard nacelles.
These will be glued to the engine cowls, which will be glued to the wings with PVA/Elmers, so that they can be replaced if necessary.
I would recommend getting 1.2 or 1.5mm dia longer shafted electric motors, just to make fitting the props easier, wired to a rheostat speed controller connected to 3x AA batteries at 4.5V.
The LED's will be wired to a separate 2x AA 3.0V batterypack with resistors when I workout how to get the different colours & sizes needed evenly illuminating.
I will post pics if I get time.