HAHAHA thats some funny shit.
7M's don't have a crankshaft position sensor. Whoever told you that is either A. lieing, or B. never worked on a MK3 supra before and is just repeating what a hack mechanic told them he replaced. Either way, there is no Crankshaft position sensor, ask me how I know.
All 4 huh?
Too bad a 7M is a 6 cylinder.
Too bad retorquing 20 year old factory head bolts don't do a good god damn. The damage is already done with the head bolt threads being caked with carbon and they are already streched.
Theres a reason the car is selling for $1000. Sounds like a complete toilet to me.