It was quite obvious when my ignition switch fried since smoke started coming out of it. It melted wires going thru the tach so if turns your switch did short that may be a place to look for damage. If you do want to keep the original type switch I bought Lucas p/n 34680 and I was able to remove the key tumbler and install the original one from the original switch so I can still use the original keys. 34680 seems beefier and much better quality than what came out of my car. Has been working fine for about 10 years now.
David Barnes
68 E-Type FHC