Agree, Agree, Agree neither myself or Dorian would be able to say if the SC is OK as they all vary immensely, what I was suggesting, if your heart is set on this car, that prior to inspection you have it put on a dyno at a respected tuners who would be able to give a plot of all readings and most importantly AFR mine was running 16:1, however I still believe that the someone has looked at this car for performance as one of the pictures does show a AEM gauge which again this wouldn't be fitted for bling.
The noise thing is spot on, it does clatter, chatter whatever, and you do get used to the noises, BTW my oil at the moment is being changed approx every 300miles 10w50 it gets changed when the clatter gets louder with an attributed lumpy idle.
......and IMHO Dorians first and last lines are spot on, do it yourself, don't buy this car too many unknowns,
and sorry to whoever owns it