hiya Ltn.....first of all welcome to the forum
a week is a very very short time to be looking for a donor, best to try and spread it out while you can be getting on with other stuff like chassis building and of course a build table, produce your own cp kit etc etc there is loads of "other" things you could be doing pertanant to the build, as for sourcing a donor quickly ...try Ebay, Gumtree, Pistonheads, Preloved there are loads of online sites to check, then there is your local adtrader mags and Autotrader .....when out driving keep an eye out for neglected cars sitting with grass growing all around them (some times can be had for free) ask friends and familly to put the feelers out....if you have done all this and had no joy then give up and get the meccano or lego set out and start from there
seriously be patient, one will crop up.... just get on with the "other stuff"