Rocky is just gorgeous - I love those big tabby tommies!
Cats usually do not show stress in the same way we do. For example, I have an extremely feral cat I'm in the process of trying to tame enough for adoption.
She seems calm enough, and lets me pet her now. However, she is overgrooming her tail, and that is a sign of stress.
Let us know how Rocky does!
p.s. Getting toms neutered at 8 months old is chancy. They are old enough to start spraying at that age, so someone who is not prepared to deal with that should get them done at 6 months.