Are you running the Rochester carb that was original equipment on the 250? If so, you can probably swap the choke cover from it to the new carb, assuming the new one is also the same brand and type of carb. The problem will be with getting hot air to it to make it release.
An electric choke heater is the simplest, and most reliable way to run an automatic choke. How difficult is it to run a pressure switch and two wires? An automatic choke is smarter than all drivers, and most mechanics. It works when it's needed, with no input from the driver, and doesn't forget to release itself when the engine warms up.
Jerry
