2005 Volvo S80 B5254T with 186,000 miles. I have 0 compression in cylinder 4

What is your question?

The remaining cylinders are all about the same and the compression is reasonable for the miles (155 PSI not warmed up) I know I have a valve problem or piston issue. Problem is the head needs to come off to resolve. Even if it is the valve problem lesser of the 2 issues. I'm leaning toward changing the engine out for one with lower miles. I have had 0 issues with this car since I bought it in 07 with 15K miles. The car is still in good shape everything works. I normally do everything myself timing belts/brakes/tunes ups/PCV system. I feel like I can change the engine myself but I'm curious what it would cost me to have someone else do it?