Depends upon if you want single stage to stay more original or base/clear.
On my 70 yellow B2, I used PPG concept single stage and it came out very nice and I would use it again. On my white 70 Mach 1 that was painted back in 2005, I used the Dupont Chroma and it also came out nice, but I like the PPG more.
On another classic car (non mustang) I did, I used PPG deltron 2000 base/clear, and that paint looks 1" deep.
just my 2 cents
Tony