You got lucky in that you found the problem before the seat
disintegrated and fell into the #4 cylnder. That's what happened
to my '94, I had to change out the #4 piston as it got pummelled
badly. Most machine shops replace the intake seats with a stainless
steel one that wont come out. You could try your luck at the
bone yard but it's a lot of work to change out a head and the
machine shop will also grind the valves and clean the entire head.
Yea, it's more money but at least you wont have to do it again.
let us know if we can be of any help and good luck..