I'm having problems with my ignition switch in my 78 blazer. The key cylinder keeps falling out of the steering column and when I turn the key on, the cylinder seems not to want to turn easy. So I want to bypass the key all together and put in a mometary push button starter switch and a on/off kill switch. I found the wiring diagram for the ignition, but can't really understand were to splice or cut it in at. Also how do I find out what size switch I need as far as amps go? Below is a pic of the wiring diagram. Any info would be greatly appreciated.

The picture you've got there makes no sense to me. Basically what you need is a good toggle switch and push button. Run a 10ga wire to the switch. Then run a 10 or 12ga from the switch to the positive terminal on the coil, or positive terminal on the HEI distributor cap(whichever you have). That takes care of ignition. Next you run a 10ga from the push button to the solenoid on the starter. Then power the pushbutton with a 10ga wire that is either hot all the time, or powered from the switch you wired in for the ignition(if you don't want to be able to crank the engine with the ignition off). If you go to any race shop or look online, you can get a tricky ignition switch panel that has everything you need on it.

http://racersauction.com/auction/lotImage/ign.jpg

if that is an accurate diagram splice the pink and dk green wires coming into the ignition into a toggle switch with a constant hot on the other terminal. Run another wire from the terminal with the ignition wires to a momentary on switch (push button) and wire the other side of that switch to the positive terminal of the starter solenoid. As far as rated amps for the switches try to go above 40 amps (or wire in a realay) that way if there is a surge in the system it will blow a fuse instead of burning up you toggle switch.