
Unfortunately even if there was someone with that accidental mix (fairly unlikely as Viszlas are by no means common) then there is very little likelihood that another pup of this cross would be anything like your previous dog.
Even with a full typical pedigree where you can at least be sure of the physical characteristics being pretty similar one from another, and to some extent some of the main drives and behavioural characteristics being predictble, you still find each and every dog is an individual, and it is never a good idea to compare one to a loved departed friend, as it will only lead to disappointment.
It sounds like your dog took the major part of his heredity from his sire size wise, so I suggest looking into Viszla rescue for a new friend, it may be that they get the odd crossbred one in. Contact the breed club who will be able to advise the rescue contacts, or for that matter reputable breeders, if a puppy is what you want.