valve seats concerns T/A 340 Heads

Looking for some guidance and suggestions, My heads have been cleaned up, machine shop says someone has installed valve seats and many are 25 - 60 thousands too deep which I can remember when that was done in the 80's.

Scary parts is recommended replacement with oversize seat inserts with risk of cutting into water jacket.

These are 340 T/A heads so I am stuck fixing what I have. Maybe taller seat inserts?

Photos tomorrow.