[Jason Oldfield]

Just got my rulebook today. According to Section 8:4 of the General Regulations - Electrical / Control Section (Page 90), it states:

Master Cutoff
Mandatory when battery is relocated, or as outlined in Class Requirements. An electrical power cutoff switch (one only) must be installed on the rearmost part of each vehicle and be easily accessible from outside the car body. This cutoff switch must be connected to the positive side of the electrical systems and must stop all electrical functions including magneto ignition. The off position must be clearly indicated with the word "OFF." If switch is "push/pull" type, "puss" must be the action for shutting off the electrical system, "pull" to turn it on. Any rods or cables used to activate the switch must be minimum 1/8-inch diameter. Plastic or keyed switched prohibited. Switches and/or controls must be located behind rear wheels on rear-engine dragsters.

So, from that, 1/4 turn switches are still legal.