Go to the Drag Racing section on this forum. Towards the top of the page is a link to NHRA rules from the 1960's including 1968. I found it very helpful for projects such as this.
Really nice looking replica. As far as your one and only build, when it comes to models, quality beats quantity any day and this looks like very high quality work to me.
I don't know how I missed this until now but that is one really beautiful model.
The paint is perfect and the interior work is over-the-top!
Very well done!