Hey, Hey, Back off on the old Soares, this is a real soft spot with me, got an 87 model myself (generation 2)
Anyway Nate, with your engine options, the 7M-GTE manifolds and injectors will most likely not bolt up to the 5M engine, plus the CT-26 Turbo found on the 7M engines are all getting tired at this age and will undoubtally need rebuilding. Also the standard ECU on the 5M will not take to boosting well as all the fuel maps will be thrown out.
Allthough I have seen some tough turbocharged 5M engines in Japan, your best option is not to waste your money on it, a much better option would be a compleat engine transplant, either the 3 litre 7M-GTE or the more reliable 2 litre 1G-GTE. At 210hp standard from the little 1G, it makes a very cheap and easy way to get your Soarer doing mid 14 sec passes, trust me ive got one!
PS where are you?