I took my 73 Challenger out for it's 1st test drive yesterday and the transmission doesn't up shift right or down shift right. It takes off ok in 1st but will not shift into 2nd till about 25mph and won't shift into drive or 3rd till between 50-55 mph. When you slow down it shifts down into 2nd at about 40 mph but shifts down into 1st gear fine at a slower speed. The transmission was just rebuilt with a transgo shift kit installed. I'm not a transmission guy but I have adjusted the kick down linkage per the shop manual and even tried changing from that but can't get it to shift at lower speeds. Any help would be great but I can always take it to the transmission place that rebuilt it but I hate leaving my old cars anywhere. Thanks in advance.