I think it is foolhardy to attempt ctb with poisons, any poisons, that have absolutely zero track record in producing certain death. I'm not calling you a fool, or anything like that, I'm saying your actions, utilizing this made-up method, would be foolish. The likelihood of you being successful (death) are slim to none given you know absolutely nothing about these chemicals, and you haven't even decided on, at least, one of them, or at least haven't gotten it, yet. The odds of you fucking up your internal organs is extremely high. Now, picture yourself with the same shit going on in your head about wanting to kill yourself, only now you've got a whole bunch of physical conditions to deal with, too, like kidneys that aren't functioning correctly, and a liver that works half-ass, and probably a ton of other issues, as well. You might end up so bad that you can't walk. Where would you be then? You may be unable to try anything again to get yourself out of your new found misery.
This is exactly the reason for sticking with methods that you know have at least been successful most of the time, even some of the time, in the past, instead of inventing your own. All I can say is good luck to you if you go through with anything even remotely close to this method you outlined.