timing hole threads buggared

Does anyone know what size finishing tap I need to clean up the threads on my timing hole ('77 shovelhead).

5/8" -18 thread for '70-up

Thanks, Lucifer. HRK, I'm gonna have to retime it anyway and I figured I might as well try and fix the threads. I took a greased q-tip and carefully cleaned out the hole, then used a couple of q-tips with some brake cleaner on them and wiped the hole clean. It's definitely crossthreaded.
I have the tap and am waiting for it to warm up a bit before trying it out. Parts went out today to Prodrag.

Use lotsa grease on the tap and clean it often so any shavings stick in the grease....You could also do what you said about the Teflon tape,wrap it and if the plug goes in snug as doesn't leak and you can live with that...I't not like you're going to be re-timing the engine very often....

Today I greased the tap and got the hole cleaned out. Plug goes in & out smoothly now (no porn intended LOL).

Temps will be going up into the low to mid 60s by next weekend. Go figure . . .

Thanks; I'll remember. Right now it's a waiting game. I've done all I could up to this point. It's gonna be interesting to see if the cam seal leak finally gets stopped. It's the "last leak" to fix.
Will be ordering a new 3/4 helmet & face shield this week and hopefully by around New Years I'll have everything together and ready to go. Changed the oil/filter already and will be changing the points & plugs, too. Then it's time to take this ol' kick start, jockey shift, suicide clutch ass beater on it's maiden voyage.

Looks good JB and now everything should run good. Have fun.