I did autobody professionally many years ago. The metal on these old cars is 18ga, which is much thicker than today's cars. The dent needs to be attacked from a number of different angles. First from the inside a dolly needs to be used to put pressure on the dent while at the same time using a shrink hammer to begin knocking the metal upwards from that high spot at the bottom. You do not want to beat the hell out of it and stretch the metal or it will oil can as others have eluded to. Once it starts coming out I would use a stud welder on the body line to begin pulling that out where it needs to be. Likely with a clamp so you can grab multiple stud when pulling. Some hammer and dolly work will be needed there as well. As for the door gap, once the dent is slowly being massaged it will come back to its original location or close to it, it may need a little pull as well. As you work it out you need to continously run you hand flat against the panel feeling for high and low spots and working them out with a combination of the hammer and dolly and the stud welder. You can use a straight edge to help gage some of it depending on the curve of the panel. Some shrinking may be necessary to tighten up the metal, that is done with either a torch or the stud welder.