The Stovebolt Site Forums The Shop Area Driveline dot 3, 4 ,and 5?

i did a search on brake fluid last night and i decided to use dot 5 over dot 3. i weighed the pro and cons, but when i went in my garage i found out the i have dot 4.(castrol dot 4) so i need advice. it's a 1955.1 3600. my old single master cylinder was leaking and one wheel cylinder failed. ( both of those were about five years old) so i decided to redo the brake system . new double master cylinder ,new hoses, new nicopp lines. all the old fluid is drained away. everything is installed and ready to go. i want to remove the master cylinder for a bench bleed. now i just need a solid answer of what fluid to use because i'm using older wheel cylinders in front newer cylinders in rear and i don't know what type of fluid was in there. am i over thinking this. thank you, brian