Barnfind49 has a solution for a 4L60E to original speedo, search his posts for the details.
Looking good, you are really making progress!
Thanks! I found the post
HERE but have found better prices another manufacturer's website
Speedbox GPS/VSS to Cable Speedometer Converter.
Last night I got my taillights and brake lights wired up as well as the bumpers set in place on jack stands.