Greg,
The trans you're using will determine the best approach to the throwout system. If you are using a deep bell housing (T5 or Tremec), the concentric release is the easiest system. Using a fork requires a spacer under the pivot and fiddling with the slave bracket. Details for mounting are at
http://www.erareplicas.com/427man/clutch/conc_to.htm
We use Weber/McLeod (714-630-2171) pieces, #1405-30. It's got an extra-long line.
If you are using a 4 speed, you can drill a couple of holes in the bell housing to mount the pivot bracket. I've got a pattern if you need it.