[olddog]

I wouldn't put a $ price on it, but it is not a Superformance or ERA worthy price. Ultimately when a seller and a buyer arrives at a number that they are both willing to make a deal on, then that is what it will sell for. In reality one or the other likely didn't get a good deal.

Things to consider:
The Jag rear end is a big plus for originality.
I think they have a round tube frame. That is a plus for originality.
The body and paint looks good.
1979 was a long time ago. 41 years are not kind to cars.
351W is pretty vanilla today. Today it could be stroked to over 400 cid for the same money.
The heads on the engine were likely good head in 1979, but bottom shelf today.
T-5 Transmissions are ok for mild engines like it has, but much better can be had today.
I would expect the engine is around 350 Hp.
The MG front end was used a lot back in 79. Not so much today. I cannot say how good or bad they were.
Today most use coil over shocks. I believe it to be superior. Certainly easily adjusted.
Today most put disk brakes on all 4 wheels.
I think you will find the Gas cap in the center of the car sucks.

Finding parts for a no longer manufactured car and little documentation on what parts were used will be no fun, and with the age of the car your likely do this a lot. So on the one hand it may be built better than the average FFR (that may be a stretch), but a FFR has a ton of support around it. You will be on your own. You should factor all this in and ask yourself how well are you equipped to handle this.

PS
The engine is already punched out 0.040". That is typically the maximum. Next rebuild the block is likely a boat anchor.

I guess it does have disks so you can strike that off the list.