Manyal brake pushrod length question

I did a auto to 4sp conversion and a drum to disc brake converdion on my 72 dart and my front calipers do not want to release. My question is are the brake push rods the same length for this switch. The front calipers are new and I have tried 2 different master cyclinders with a 3rd one on the way to me. The brakes will release after about 5 to 10 minutes of sitting, any ideas on what I might be overlooking.
Thanks