Those welds look like c**p.
I guess that's a TR6.
That car has a frame close under the back "seat" (bench) but not close enough to bolt to.
FIA racing rules are not eligible here but they normally require plates 120 cm² both over and under the body metal. But the mounting points for that bar are not anywhere near good enough to provide any type of roll over protection worth naming. The bar is basically for looks only.
If you're concerned about rollover protection, the minimum bar should be mounted to the floor/frame between the front seats and rear bench, have rear bracing that goes through the body to the chassis under the gas tank, and have a diagonal bracing.
This one would be good enough being a street bar with a diagonal
https://www.paeco.com/Rollbars%20and%20Cages.htm
Not that a minimum bar would be enough, but if you were unlucky enough that the car rolls over, like for example you accidentally fell off a mountain road, it would definitely save your head.
For other types of accidents it wouldn't be enough. But we don't usually drive that fast, do we?
example:
https://autoholics.com/2011/11/07/Hemi--Cuda-Fatal-Accident-in-Delaware--580200