This looks awesome, a bit pricey, but awesome! So, who is ordering first?
http://www.hiroboy.com/catalog/product_info.php?cPath=43&products_id=5913&osCsid=959bd3fc71a2692f0b28dee17766cb2b
Don't forget that '70 was the first year for Pro Stock and most cars where running mostly stock components in the suspension systems, it was later, especially after Jenkins tube Vega, that things started getting crazy.
I just bought one and it looks fine to me. I am just going to build it and add what it needs and be done with it. As a model builder, this is no big deal.
Yes, they only had two cars for '63, with the exception being the Law Man wagon that Eckstrand tested with a stick in it. But, it was too heavy and abandoned. The "Third" car was a replacement for the car they wrecked in testing. It became "980"
You can't beat the Revell Chassis for fidelity and accuracy. They are less clunky than the AMT kits. Another option is the AMT Parts Pack Chassis that was re-issued a few years ago.
In the end, use the one that best fits your needs and vision. Have fun!