Welcome to the forum.
What did the old #5 spark plug look like?
3 things are needed for a cylinder to fire
Spark, at the right time
Air/Fuel mix, in the correct ratio
Compression is a mechanical function, and while not likely the problem, you can test it and take it off the table, so just spark and fuel are left.
Spark has 3 parts, Coil, Spark plug wire, and spark plug.
On your engine #1 and #5 share the same coil, and if you are only getting P0305 code then coil is "probably" not the issue.
But you can also take that off the table if you swap #1 and #5 wires at the Coil.
1 and 5 will be right next to each other, just swap them around, and drive engine that way, if you lose P0305 and get P0301 then coil pack is bad.
Spark plug wires can be tested with an OHM meter, but you can always swap #5 and #4 or #6, which ever is long enough, and again see if code changes, P030X
Air/Fuel is harder to check, so last
Can you feel the misfire all the time or does it come and go?
And when does it come and when does it go?
I.E. cold engine, warm engine, idling or higher RPMs, accelerating only