Would giving oral sex to someone with syphilis quickly turn to neuro syphilis and would it show in standard blood tests if it were not passed vaginaly?

Syphilis: The disease is very dangerous, even today, but neurosyphilis does not develop within the first six months. Please get tested if you think you may have been exposed.

No and yes: Neurosyphilis (also called tertiary syphilis) is a slow process. It usually occurs 3-15 years after the initial infection, if that infection is not treated. The standard test will detect syphilis, irregardless of how it was acquired.