Light DME substitute question

[scarer]

Having received the ingredients I ordered to make a Vienna lager, I made a yeast starter on saturday morning intending for use tomorrow which is when I brew however I am 500g short of Munich malt.

I made the starter with 400g of light DME in 4L of water. The question is rather than decanting off the liquor and just using the yeast slurry tomorrow (wyeast 2206 Bavarian) can I pitch the whole lot as a substitute for the Munich malt?

The Grain bill as it stands for 21lts is 2.7Kg of Vienna malt and 1Kg of Munich malt (should have been 1.5Kg) 150g Crystal and 50g chocolate malt.
I've got 300g of Vienna left over as I have 3Kg in total if this is better........will it make much difference?

OR....... I could just nip to the homebrew shop and buy 500g of Munich!

What do you think?