Toyota does something in engineering that I'm surprised isn't more common.
Frequently, a part designed for a specific application will be very close to the best design for a related engine.
Many US stuff allows things that should not be interchanged to be swapped over, the poster child may be the 289/210 hp Windsor damper used with a big cam (you need the very different 271 hp damper). Chevy SBC V8 damper fits L6, B/RB early/late tappets and pushrods can be mixed up.
Toyota changes at least one feature to make sure if the part is not completely compatible with another engine - it won't go on. They change the bolt pattern of the flex plate and converter when the swap is not a good idea, even in the same transmission. Accidental misapplication is greatly reduced, the downside is everything is more expensive and you don't have the part in stock.