Hello!
Its great to hear from a neighbor. Hope you are doing well.
Unfortunately, I do not have much detail on the Old Motorbikes the late Ustaad had. I just heard it from him and his sons. No idea where the bikes went or if any were there in the first place. I would not be surprised if he had exaggerated. Or the other possibility of them having been exported out of Pakistan. Many bikes have been exported, Im sure other contributors can shed some light on this sad aspect with first hand info.
Sorry but I was unable to provide you any solid lead on this.
Best regards.