If you are blowing fuses only when you turn on the ignition it means that you have a short to ground somewhere past the ignition switch and all of your key off powered circuits are ok. The key switch powers the fuse panel, the accessories, the external regulator, the turn signals, the distributor Bat terminal,the gauge cluster, the radio, and anything else that needs key on power.
Can you detail which fuses you are blowing? those would be the circuits that are grounding. In order to trouble shoot this problem you need to know the path of the electricity from the key switch to the various switches and circuits that only work with the key on.
Do you have a multi-meter? If so then disconnect the positive battery cable and connect the meter red lead to the IGN Unfused terminal on the fuse panel and the black lead to the best ground you can find near there. You want the meter on the continuity (resistance) setting. Make sure all the fuses are good and have good contact in there holders. Make sure that all the switches are off. Heater, wipers, radio.
I would start with the external regulator plug because the key feeds the brown wire that goes there.
Turn on the key and look for a reading on the meter close to zero. You should get that if you are blowing fuses when you turn on the key. If you do.
Unplug the regulator plug. Did the reading go up? Yes, No
If no, turn on all the switches then pull the fuse for that switch and read the meter. Leave that switch on and the fuse out as you go to the next one. Be sure to take not of where the fuses go. If you don't have any additional things wire into the key switch you should be able to figure out which circuit is grounded and then you can look for bare wires or wires touching a ground.
It would take a pretty good short to blow a fusible link and I would expect to see some burnt insulation on the shorted wires.
Here is a picture of the fuse panel with the key on hot fuses and the key off hot circuits to help you. Courtesy of DJLambert.
