It will work but if you want to do 5 gal batches you'll need to sparge. For full volume mashes you'll generally want a pot about twice your batch size.
What you need to do full volume mashes is shown in the chart below. Assumes you want 5.5 gal post-boil, boil for 1 hr @ 1.2 gal/hr boil-off rate, have 0.08 gal/lb apparent grain absorption, and want 1 gal of freeboard for mash in stirring.