I verified the timing marks as you suggested. With the serpentine belt pulley off this is easier to see. They all seem to be lining up.

I re-adjusted the tensioner and torqued the bolt (13 ft-lbs). I thought this was it but after running for a while (again hot day) I got the misfire on cyl 5 again ...

I removed the serpentine belt pulley from the crank so I could see the timing marks easier on the crank. There are two small marks with a long mark on the crank. I think the mark on the block is towards the rear of the car. I cannot see it but I can feel a bump as you run your fingers down a ridge ...

I re-adjusted the tensioner and torqued the bolt (15 ft-lbs). I thought this was it but after running for a while (again hot day) I got the misfire on cyl 5 again (ran rough). I shut the car off and removed the side cover. The tensioner was in the hot position. I stared the car and the adjuster ...

I was able to drive with plugs 5 and 2 swapped and could recreate the P0305 misfire cyl #5. This again was after at least 20 min of running. Its about 80 degrees currently outside (Nice September in upstate NY).

I recently changed my timing belt/water pump on my 2008 S60 with 105,500 miles. After driving for about 30 miles in 85 degree heat the car starting to run rough and a P0305 code came up (misfire on cylinder 5). After the sat for about 10 minutes it ran fine.

I swapped cylinder 5 and 2 coil packs ...