[The Radium King]

search. this is a common topic with lots of info here. the spark plugs pass through the cam covers to get to the cyl heads. Porsche used plastic tubes for this that routinely crack and leak oil (or the o-rings that seal the plastic tubes can flatten and pass oil). this may be the source of the leak you are seeing.

also, cam covers can start to weep oil. prior to pulling them off and resealing, try just retorquing all the bolts (in the appropriate order as per the maint manual).

I doubt the price you were quoted was to remove the actual heads. probably just cam covers. if you do go this route then chain tensioner pads should be replaced. a good Porsche mechanic should know this. get a second opinion.