Yes you can call your cat a breed without papers. We had a silver tabby... A classic tabby... A siamese... Without papers ;) but to he RECOGNIZED as a breed is different.
Actually it does look similar. This kitty has muscle. Is vocal. And seems to "understand" lol. I can always ask around and ask a vet too.
As for why he would be wandering around... Either lost, stolen or someone who did not know his value.
Breed for the breed, not for the money; the words any REAL breeder would understand.
You must know nothing in order to know all, for all is nothing and nothing is for all.