I have used both Intermountain, and Athearn wheelsets in Lionel trucks. They are a little bit of a loose fit but seem to behave fine on the RR. You need to cut the coupler tang off the truck to make room for the Kadee Box.
If you decide to go with different trucks you will probably need to scratchbuild a new body bolster. The bolsters on the lionel trucks are arched higher than NMRA standard trucks, and the body bolsters are thinner, to allow room for the lionel coupler.
Just reinstalling the trucks with 3 rail wheels may or may set the car a close to good height from rails. I have converted L hoppers, flats, and boxes and they have been close enough. However, I also converted some R50Bs from another mfg and they say way too high unless the trucks were modified.