T-10 Transmission in a '68?

I am almost done refurbishing my 1968 chevelle 300-deluxe. The guy I bought it from sloppily converted it from an automatic to a 4-speed. I now have a Borg Warner T-10 transmission conflicting with my original speedometer. The two dont match up and are not calibrated. I dont know how to fix it cause the speed difference is not consistent. The speedometer is very erratic and I've replaced two broken cables within a week. Anyone have any ideas/solutions???

Welcome to the forum.
Please avoid multiple posts on one subject. It consumes server resources unnecessarily and can be frustrating for regular users.

I suggest to use your other thread to continue this discussion.

http://www.automotiveforums.com/vbulletin/showthread.php?p=5892337#post5892337

This thread is now closed.