This thread has drawn me in, so I'll weigh in.
I don't know much about 'Yoda's other than Prius, and I'm assuming this is a late model V6 Taco, so I did a quick search on the subject. I've not heard of any IC engine requiring different spark plugs in the same engine, and according to Rock Auto, there's a huge selection of what could be in there, and no calling out for a certain position. I would put nothing in there except what Toyota calls for- probably NGK- the best plug in the world IMHO, or Denso. Not shabby either.
A layout of the secondary Ignition system (I think it was a '13 MY I looked at) shows 3 coils on one bank, and a set of secondary wires going around to the other bank. They're wired up in companion, so one coil fires 2 cylinders each go'round. It's a single plug system. Very simple and straightforward.
I have some experience with ethanol blends, like E85, and they will knock down a copper plug's life by 60%, so find out what is in there, and plan accordingly. Personally, I'd by most concerned about getting those old plugs out without incident. Plug removal issues seem to by common nowadays.