、。
I'd expected a more classical kind of face, but she's a beauty who'd pass perfectly well even by today's standards.
Literal
More classical [adjectival-な] features [is-なの][question-か] [quotative-と] thought-[contrary-to-expectation-きや], current [genitive-の] era [even-でも] fully pass-muster beauty is.
Turns on a small but wonderful classical-flavored construction: ~と思いきや. 思いきや literally means 'thought… but no!' — it's a frozen classical form (from 思いき + や, an archaic questioning particle) meaning 'contrary to what one thought,' 'I expected X but it turned out Y.' It's a set written expression, almost always used exactly this way. 充分通用する ('fully passes muster,' 'fully serves the purpose') uses 通用する ('to be valid, acceptable, current') in the sense 'her looks would be accepted even today.' 美形 is a noun for 'a beautiful face / a beauty,' slightly more stylized than 美人.