It depends on what you might want to ever do with the lathe in the future. The gearbox offers only a limited range of threads it can cut. With a full set of change wheels, you can set the train between the spindle and the gearbox so the lathe will cut just about all possible pitches of all threads such as BA, DP (worms), Mod (metric worms), metric, as well as the usual BS and UN pitches. I would keep the extra gears just in case. They don't take up much room.
Brian Wood;'s book Gearing of Lathes For Screwcutting has a chart of what gears are needed for what threads, with a gearbox, and it looks like they are all needed for something. It would pay to look at that chart, or similar from Myford etc before parting with any gears.
But if all you are ever going to do is the standard thread available on the gearbox, then no need for them.
Edited By Hopper on 24/04/2022 10:54:20