Hey Bravi,
Deeply sorry to hear about your loss... Just know that he is more with you now than he has ever been before... I know it seems hard to believe sometimes, but it's true in all of its honesty/sincerity.
With regards to seeing him in your dreams as being healthier, happier, and younger: After my Grandpa died, my grandma was visited by him in spirit form... She said that he told her not to worry, that everything was going to be alright. She said that he looked like he was in his 20's again, very young, very happy, and refreshed.
While in spirit/energy form, it is possible for beings/entities to take on the appearance of anything they so desire... Most will take on an appearance that will be recognizable to others. Also, by looking younger, that gives off the impression of how they feel about themselves internally within their new loving/caring/unconditional "environment".
Also, it has been noted that the "light energy" of a being can give off the impression of who they were whilst alive in the physical world.... (no actual "need" to take on the physical attributes of who they were in order to reflect their identity.") It's moreso done for effectual reasons.
Again, my deepest condolences,
PUL,
Cosmic_Ambitions