D+R on Frame 231, boot up a savestate and test it out, if you dont have access to save states, and dont want to practice on emulator, download fceux, and make a tas to see exaxctly what you need to do, also you probably already know this, but if not, you need pellsson rom to tell what frames you're on

The reason this wouldn't work (backwards scroll or not) is because you're in the underground section of the warpzone, when the scroll lock is passed, it looks at where mario is, if he is in an above ground level or a below ground level, and then the appropriate warpzone is loaded from there. This can be proven by hacking the game to make 1-2 an above ground level or have the game treat 1-2 as an above ground level, the warpzone will load the 6-7-8 warpzone

Im starting to look at practicing 4:57 attempts, but i dont know what delays are