Can i successfully use old Early American flyer 3 rail curved track with, o gauge lio

I have prewar American Flyer both Chicago Flyer and AC Gilbert. I have boxes of original track and switches. The only difference is the Flyer radius is 20". Lionel used 13 1/2" radius (O27), 21" radius (O42) 36" radius (O72) I know I did not list all of the radius offered but you can get the idea. I also have some Lionel and MTH products in O scale. They run fine on Flyer track. All you have to do is make sure that the radius is large enough for the locomotive.

Example: my prewar M10000 needs 36" radius track, Flyer is only 20" and cannot be used, However a modern MTH subway set will run on flyer 20" radus track with no problem.

I WOULD USE LIONEL 54 OR 72 INCH RADIUS TUBLER TRACK! STAY WITH ONE COMPANT!

There is no difference in way the track was made between Flyer and Lionel, You can interchange the track as you please. The only real difference is in the switches, Lionel cars and locomotives with the sliding shoe for the coupler do not like flyer switches I have heard. Modern Lionel and MTH cars and locomotives do not have that issue and I have operated them on Flyer track and switches with no problem. You just have to have the correct radius for what ever you are running.