Wow great! Thanks for the info. I greatly appreciate it. Looks like I'll try to keep the SM420 in it and if I were to blow it up I'll look into an NV4500 5 spd. First gear is up to 6.34 but it's not like I'll be towing 20,000lbs. I appreciate the help.
I do have the original everything at this point including the original rear. I would like to find a way to get the gearing down to drive in on the highway but I hate to do an axle swap. I love the original look with new technology hidden.