Man.. No one is trying to be a jerk to anyone.. but this has been discussed a lot on the forum.
The only way you can definitively tell on a 1964 Pontiac Lemans If it had the gto option is to get a phs from the Pontiac Historical Society.
There is no short cut to this.
And technically all 1964 GTO's are infact Lemans with a GTO option.
Save yourself a bunch of headaches and just get the PHS from the PHS services. One that is handed to you by the seller can be faked as well. And I would not even trust like Barret Jackson or Meecham. They are clear that they are not responsible for misrepresentations.
The ONLY one I would trust is the one coming from PHS delivered to you by PHS.
And if anyone thinks a PHS cant be faked, send DM to me of your VIN number and I will make and entire packet up for you for FREEEEEEE... Act I will not, But I can post the template with a fake watermark. Actually I will make one this weekend with a VIN of a random car. but it can totally be done.
PHS Automotive Services, Inc.
it is 75 dollars, and will save you tons of time money and frustration from someone trying to pass of a lemans with a gto option.