Problem with alternator upgrade on my 72 C-20

[timmyl75]

i was having a problem with my truck starting after it ran for awhile found out it was a timing issue. but in the process of fing the cause i was checking the alt. to make sure it had good out put to keep the battery charged. sometimes it was reading only 11 volts then it would read 17 volts. so my father in law which is a heavy equipment tech. told me it would fry my battery and maybe that was part of the battery not holding a charge. he said the replace the external regulated alt. with a internal regulated one. so i searched the boards and found some info on how to wire. so i did the wiring and replaced the alt with a internal regulated alt. but i forgot to disconnect the battery when hooking up the hot wire and got a few sparks from the back of the alt. then i remembered to disconnect the battery. finished up the install and all wiring. now on to the problem when i connect the battery the truck wants the start. i took all the wiring off the alt. to rule out the possibility of a shorted alt. and it still wants to try to start. could it be possible that i fried the ignition switch. or is it something else that was already there.

thanks for any help in advanced
Tim