I have no experience w/a dog w/no teeth, but I would think you can wet the kibble & give it to him soft. Canned food is actually better than kibble, it has more moisture & is nutrient dense. You're right that the 'cheap' canned might not be the best, there are a lot of good ones. Make sure you don't restrict his protein, seniors need to keep their muscle mass from deteriorating, so they don't necessarily need 'senior' food.
ASPCA | Feeding Older Dogs Avoid "senior" diets that have reduced levels of protein. Studies have shown that the protein requirement for older dogs does not decrease with age, and that protein levels do not contribute to the development or progression of renal failure. It is important to feed older dogs diets that contain optimum levels of highly digestible protein to help maintain good muscle mass.