Rear seatbelt location

I would like to install (2) rear seatbelts in my ’64 Barracuda. I’m looking for information as to where the anchors should be located. I found an article written in 2003 by Neil Brommell and published on The Early Valiant and Barracuda Club website. Although informative, it did not provide definitive locations for drilling. Does anyone at FABO have any information concerning location? Actual dimensional locations would be great and photos showing location, both interior and underbody would really help. Thanks.