I wanna make something like 454 fast track or endless and chop a bunch of my songs into one long seamless track project could someone help me??

Your music would have to be built like that from the beginning, Endless speaking. Built in mind with logical seamless transitions, sound, pairing & pathing.

Or you can make "one single long song" then divide it at points where it makes sense.

But for stuff that exist already you cant just randomly do it or else its gonna sound sloppy, or youre gonna have to rework every tracks at least beginning n end a good amount.

listen to Almighty So for inspiration

DJing look it up