I guess that depends on a persons opinion. People restore muscle cars with little more than an original firewall and someone will still buy it. My opinion on a race car would be at least the original chassis since it's hand built and any other part that was hand built or at least remade by the original builder and the rest would have to be original period correct manufactured parts. I imagine most collector race cars are considerably less than 100% original, Most people didn't think to save them or they were crashed and rebuilt multiple times before being retired. Bob Trostle posted a picture of a car he fixed that was one of his, I would still consider it an original for the most part since he did the work. Here is what his post said

"here it is all done and ready to go to Australia this is chassis #344 built in June 1985 this car was driven by Max Dumesney that summer and during the Knoxville Nationals Max beat Doug Wolfgang in the Race of States that was the only race Doug lost in about 20 `races I sold this car to Butch Hanssen from Sioux Falls he raced it for 2 years then sold it to someone else who crashed and I got it in 1990 so it was about time I did something with it Lucky John Cooley is the proud owner"

Roy wins. Oldest it could be is mid 80's. To much frame work out front and wrong cage mounts to be any older.

Just the construction of the car denotes mid 80s or newer. The triangular construction etc. Looks like they just cut the cage and put some classic body panels on it.

No reason for me to feel bad chopping it up further then. Got to have more leg room and a cage back on it.

I would still like to keep it looking like a sprint car( my daughter would kill me) but can't help but wonder what kind of looks it would get if I put my Blown 6.0 in it with this injection on top.
I'll probably just stick with a naturally aspirated engine but still might be a LS3 instead of the SBC.

Looks like it could be a Nance car with the bracing in front. Laverne built a lot of those cars for the boys in the NCRA.

There is a NICE, Nance car for sale on Ebay right now, it has some similarities to the car you have, only this one is ready to race, no redo this, and redo that, slip in your PG, and put your required lights on it, may cost more up front, but this one is not a hack! Bob

Those aren't nance quality welds

Not saying it is a Nance built car, but the tank and rear bumper have that look from about 1981-82-83 that Nance had. Maybe from KS/Okla originally?

The Nance is very nice and I would consider if I didn't already own this one. My car needs some work but Bob “Booby” Thompson at Jockos Sprint Parts said he could do the work over the winter so I know it will be done right and safe.
I actually like the idea of starting with what I have because then I can build it to my taste, I'm probably just going to redo the brake and fuel system and put on the parts required to get it titled then I'll tear it down and have the cage added and add about 6"-8" in the drivers compartment and possibly put the LS3 in it complete with EFI so it will be as simple as jumping in any other car and driving away. I already have a new wiring harness and lights and LS3 sitting in the shed so I don't really have much to buy. Motor plates are cheap and the LS3 will adapt easily to the powerglide and it should all fit under the hood without modifying anything. As much as I would like to turn it into a hot rod sprint car it will probably be done to look like an authentic sprinter ready to hit the track.

It will be cool to see it when it's done!