1974 vw beetle wiring problems

i have a 1974 vw bug and i think there may be a problem with the wiring but cannot find any specific way to fix it. the symptoms are that it sometimes does not stay started. when i turn it over sometimes the key will not stay turned and the car will shut off. very hit or miss... my brake lights stay on when my headlights are on. but they work fine when they are off. and when i am driving sometimes when i use a turn sygnal the car will shut off and not want to restart? any info would be a help this is kicking my ****... thanks in advance.