Looks can be deceiving, without a detailed copy of parts and labour invoices and a photo record of the ground up rebuild it comes down to taking the sellers word. There is a wide range in the meaning of ground up restoration. I note this seller often has rare 70's Italian bikes for sale and they show well in photos but an in person viewing can reveal a very different bike.
Can it sounds like you have dealt with the seller in the past? I was interested in. laver da 750 SF he had for sale and was even contemplating a part trade. Sounds like I should steer clear
Cheers
Jim