My bros wouldn't do it .
We used to compete in cross country trials in Land Rovers ,so we have a lot of experience in broken springs .
The problem is that sometimes the outer layer of steel can be very brittle and shatter .Also the thickness of the outer layer can vary a lot and you can never be too sure what you have got . Springs seem to sag [or invert] over a large curvature ,a press will bring them back to shape better than hammering . However if the mechanic was highly skilled ,the steel heated to the right temperature ,the hammering done expertly over the length of the spring without reducing the thickness of the metal and producing localised stress and the metal quenched correctly then it could be done succesfully .
Like I said in an earlier post , very often the local spring shops will custom make springs for you . If I need new springs on a pickup , I will have them made with first and second leaves folded around the shackle bolt [ the second leaf is a loose fit ] and a bend profile to suit my requirements .

Ironically the best rear springs we found for Landie competitions were Ford Transit springs [ just a single parabolic leaf] .