Relay Wiring for Dummies like me

[cst350]

Ok, I want to wire a kill switch to my distributor. I want to use a small switch so I need to use a relay. I go online to search for relay wiring and I get so many options I don't know which one will work. I need to know what numbers should go to:

Wire from ignition (That I will cut)
Wire going to distributor (other end of wire I will cut)
Power for the relay (12 volt from fuse block)
Ground (putting kill switch from here to chassis ground)

I think it goes as follows:

86-Wire from ignition (That I will cut)
87-Wire going to distributor (other end of wire I will cut)
30-Power for the relay (12 volt from fuse block)
85-Ground (putting kill switch from here to chassis ground)

Also, should my 12 volt from fuse block be a certain fuse size? Do I go for 12 volt constant, ignition or Accessory?

Any help or comments appreciated!!!