It is true that a phase converter can be installed to run a 3 phase machine on. You can also swap the three phase motor out for a single phase motor, so don't let the motor be the only determining factor in your choice.
Operate the cranks and shake the compound. That is the machinist's version of kicking the tires. If the machine is under power, run it and listen at several speeds. Does either have a taper attachment? They are rarely needed, but they are indispensable when you DO need one. Steady rests and follow rests are available as aftermarket accessories, but the originals go for pretty good money. If you can get at least the steady, you are way ahead. The machine in the photo looks to be in pretty good condition. See if you can talk the owner into throwing in some boot, like chucks, centers, tools, etc.
Clemson