Moving your existing bar con shifters probably isn't in the cards.

The question is what you have on your down tube where you want to install new shifters.

If you have mounting studs under the down tube cable stops, a pair of down tube shifters will probably be a piece of cake to install.

If your bike doesn't have such studs, you will probably have to search for some clamp-on shifters that have a clamp size to match your downtube.