weight loss query

Hi,

I'd appreciate an opinion on the following please -

I clocked 2.23 for the marathon in 2008 weighing approx 69/68 kg & 30.52 for km

Through stopping eating excess confectionary/cakes my weight has come down to 63-64 kg
I'm not doing the volume of training I was doing whilst training for the marathon, perhaps 40 miles per week. It's not dificult for me to keep at this weight and I feel fine, clocking 30.50 for 10 km recently.

Is it possible to predict what sort of marathon time I could possible do if I keep at my current weight and revert to a marathon training schedule similiar to what I used in 2008 ?

Thanks,

Mike