im getting another mk3

[Supra2NR]

now i havent askd a questin here in a minute
but here goes

once again i am buying another mk3
its a 87 7mgte targa
it jus had the head gasket blown and replaced
and he says he has 175xxx on the odo

now
1) how would i know that the headgasket was done right?
2)how can i tell if its the original engine that came with the car?

this are only two up-front questions for now
more to come
please help a fellow mk3 lover