Electric fuel pump

I am converting my mechanical fuel pump to an electronic can I plug the return line from the old pump to the tank and just have a line in to the elec. and a line out to the carb

If it were mine I would add a tee in the feed line to the carburetor and keep the return line along with adding a restrictor of some sort to the return line also. (small plug with a hole in it would work)
Keeping the return line can aid in fighting vapor lock, etc.

It can be done but you must include a pressure regulator. Including a bypass is best for the reason ok4450 pointed out. You can always include it later if you leave the line in place and plug the end. Depending on how the pickup is routed and the pump’s ability to suction, pump placement might be critical. It’s not uncommon to have to modify the tank outlet method or line routing to get it working properly. Just a heads up…