Wow! You really did it didn't ya?
Ok , First to test the solenoid, get out your jumper cables, remove all the wires from the Big side bolts, leave ground side of battery hooked up, and hook power to the "S" terminal..If it's working, It will go "Click" ...
With a DVOM, , set to Ohms, R X 1 scale, calibrated to 000, measure across the big bolts (one probe on each side) and read it, with the "S" wire not energized it should read infinite.
With power to the "S" side, It should read 000..If you read 000, in the non energized position, you have welded contacts , replace the solenoid.(why the starter ran away)
On the Ignition switch, If smoke came out, It can't be a good thing..crawl up under the dash, and inspect the wire harness for melted wires. (you may have to untape them.) If they are good, (not melted into a glob) Pull the switch, measure with your ohm meter from the power ( hot at all times ) to the "Run" Position with the key on..it should read 000.
Then rotate the switch to the "Start" position, It should read 000, then infinite when rotated back to the "run" position. (for this you will be required to grow a third hand..or get a bud to help.)
Do the same with the ACC position.
Be sure none of the positions read any continuity to the switch body..If they do, or one or more positions won't read get a new switch.
Don't even worry about the regulator just yet..Get it running again first..With it running, If it's putting 13.95 to 14.4 volts across the battery, It's working.