Glad to hear that someone was even trying to fix this coin. Thanks. What do you mean "Choose or create a new wallet". Is there a template we can use? Sounds like a big project. How many people do you think are still holding ecash?
Due to the issues with your current chain and the high number of coins in circulation, it does not make sense to work on the existing wallet and chain. You must therefore either code a new wallet or copy one. Coding a new wallet is possible but does not make sense due to the effort involved. Your best bet would be to do what all the scam devs do, take an existing wallet of anther coin, change the coin specs to what you want it to be, find and replace the name to the name you want, replace the graphics and put a premine in the first block. Then swop the new coins for the old. You need to get someone with coding and wallet experience to do this for you and while you are looking for a new wallet, you can just as well choose one with some features that you deem to be adding value.