PLEASE HELP!! Good buy or no? Toyota Supra 1994 TT Mark IV 30k Miles, need engine help!?

So this guy is selling a 1994 Toyota Supra Twin Turbo Mark IV for $16 and its had a lot of extra's that come with it which is cool and the best part is theres on 30k miles on it! But heres the catch i noticed he said its has a JDM 2JZ-GTE motor with JDM 5 speed transmissions R154 so it looks like he did an engine swap from a 6-speed down to a five speed. He said that it needs a usdm engine harness and a custom downpipe which sounds like his swap didnt hold up too good but then again i might not even know what im talking about lol. I'm not very good with cars so i ask for your opinions and your help on whether or not this is a safe buy or even a good buy..Please help!! Thank you