Using my Lick index analysis tool and my Lick models, I have analysed the
indices given for M67.
The models are based on the empirical calibrations of Worthey et al.
(1994, 1997). Both my models and my analysis method are described in Lilly
& Fritze-v. Alvensleben 2006, A&A 457, 467.

My results for M67 give an age of 5.52(+-0.2) Gyrs and a metallicity of
[Fe/H]=-0.2 dex.

I have attached a figure showing a comparision of my "best fitting" model
and the given measurements by plotting the respective index strengths (Uta
can explain it in depth - just note that only the indices with error
bars which I took from the corresponding paper were taken into account
for the analysis). It shows how well the measurements are reproduced by my
best model.