Kerry and JP are making a great point too, you need to decide your end goal with the car first. Both in power and function.
But why bother with an ls swap in a hooptie, when the supra with the 1jz-gte is proven capable with the same kind of money you are willing to put into the whole ls swap? Upgrade to a big single, stud the head, bigger fuel pump/injectors, ecu/tune and you're done. The 154r is good for around 500hp reliably stock, and 900+ with a mild rebuild kit. Hell you could have all the parts shipped and installed in a weekend.