Data entry of 350 cards is not that difficult to do. You will be pleased to know that i used to do this type of data entry throughout my summer internship. At first my only job was to open the visiting book and start copying data onto excel. It was one of the first few things I learned during my internship. And now, I can do this work fast and error free.
I will take 2 days. I know that is a lot, but i will make sure the data is error free. Its better to wait and get perfect work rather to do it quickly and get disturbed due to errors.