Scholarship both conservative and liberal usually puts the dates of the gospels after the destruction of Jerusalem in AD 70. In 1976, John A. T. Robinson, hardly a bastion of conservatism, argued in Redating the New Testament that all the NT books could be dated before this event. He came at it from several angles, but I think I may have found one he missed.

Matt 27:8 says the field the priests bought with Judas' money was called the Field of Blood "to this day."
Matt 28:15 the fake story from the soldiers is still circulated among the Jews today.

Both statements suggest that these things were going on in a non-destroyed Judea and Jerusalem. After the Roman trouncing, the Jews were scattered all over the Roman empire, as we know. So these two subtle statements seem to indicate that the temple was still standing, the field was still called akeldama, and the soldiers were still spreading their false tale.

Any thoughts?

You would think the fact that no one mentioned the destruction of Jerusalem, especially in passages such as Matt. 24, would argue in favor of a date prior to AD 70. John didn't mention either, and his gospel is widely dated as post AD 70, but his book was less historical and more didactic, so perhaps that would explain it.

Agreed, Robinson's reasoning convinced me 30 years ago. But I'm mainly interested in these specific phrases as ways to determine the latest possible date the book could have been written.

I've never heard your evidence before, but I would think it is compelling.