Hi Jason .
This is a matter of if you use the dealership or a known good Porsche repair shop .
V6 engine will be around 15.8hrs X what every the shop rate is ,$50 ,$80 etc .
Gasket kit for the $260 and $360 Victor HS54629 Engine Cylinder Head Gasket Set
The "S" with the V8 is 26.5 hrs .
Gasket kit will be around 80us each head gasket .
Will check what the set cost and get back to you.
Kind regards Greg
Valve cover set will also cost you around $80us all this can be found on Ebay.
At a dealership you could be up to $3200 to $4000 just in labor .
parts up to $900 to $1300us.
At a local repair shop that has experience with this vehicle will call around $85us +per hr.
Need further assistance then please get back to me .
Rgds Greg ,