Ignition Module Question

Long story short, I bought this 73 Duster w/ a 318. After sitting for 2+ months due to complete roof replacement ect, I tried to start it up. The wife's nephew who claims to have worked at a shop before put the battery on backwards. Some smoke came out of two separate wires so i took the cables off the battery, never turned the ignition key. I decided to change the ballast resister, voltage regulator, and the ignition control module. I noticed this sticky black stuff on around it and after taking it apart I discovered that the black stuff (not sure what the proper term for it is) had melted off the module. After replacing the mentioned parts the car started and idled fine. Is there a reason as to why that melted and is there something that I need to check to make sure this doesnt happen again?:newb: