Degreeing my camshaft

I am going to be playing around with degreeing the camshaft that is in my truck now too see where its at. I plan to do this with engine in truck and hope to not run across any problems.

I have rad. and A/C condenser out of the way so it looks like removing the cam ( eventually ) and replacing it with a re-grind will be do-able.

I have had these two degree wheels a few years, the blue one the slant bolt is nice and snug on, the black one the hole is a bit larger so sloppy, I am assuming there is no problem with using the blue one but its worth asking cause this is new for me.

Id like to have a larger one cause its easier to read but hoping this one will do fine.

I also need to get my own piston stop tool, I know one can be made but its easier for me to just spend the 10-15 bucks and buy one. I see them with different features like pressure release and also see different M.M sizes listed.

I dont know what millimeter size plug slant has.

Can anyone recommend a good one to buy?