DOT 5 vs 3 debates can get heated. Most either swear by 5 or swear at it. It has a big advantage of not absorbing water like 3 will. However, it does not have quite as good hydraulic properties as 3, making it harder to bleed. It also doesn't give you quite as good of pedal response, but most people will never know the difference on that part.
If you plan on driving the vehicle at least once a week and don't mind flushing the system every two years, go with 3. Otherwise, take a serious look at 5.
As far as Carters kits, you will have to call them. Their customer service has not been praised by anyone here for some time, which has sent a lot of business to Chevy Duty or Bowtie Bits. Both (and others) are in the links section.
