Change Control Types (but not names) on Form with Minimal Impact

I need to change a lot of textboxes to NumericUpDowns and other similar changes on some forms in my multiform c# app. I'd like to keep the name of each control the same as I make the change. There's also code for events associated with some of the controls that I'd like to change as little as possible. How do I do this without screwing things up badly in Visual Studio? It's version 2008. I'm worried I'll surely run into the dreaded designer errors.