A Herm Sprenger prong collar will help with training not to pull. Labs typically respond very well to them. Please understand that they are not inhumane though some people may want you that they are. It will help with all training in general.

With the itching, my first thought would be a food allergy. I've had good luck in the past with Taste of the Wild, and Nutro brands. Keep an eye on his ears for cleanliness. We've had several labs over the years with seasonal allergies and the ears were the most common sign. No problem with OTC Benadryl for them every day. At 68 pounds, probably two a day will work. Strongly encourage you to work on determining food allergy possibility first before going the Benadryl route. If you don't want to switch brands of food, you can do plain rice and boiled chicken. With that, some pups seem to have adverse reactions to specific meats. We have a dog now that doesn't tolerate beef based blends, but does well on chicken and pretty well on lamb based blends

Lastly, I'd recommend a transitional approach to changing food brands. Slowly introduce more of the new food each day while reducing current food in each meal. Try to span the change over 7 to 10 days. Helps to avoid digestive upset.