trans linkage

Hi guys , I have a '72 Scamp , 383-727 . engine and trans are new . Trans won't shift to 3rd. In neutral, the car will start but it will be in gear . shifter won't go into low . I have a column shifter and I would like to keep it . The shift linkage is cobbled up stuff . Does anyone have any suggestions OR where I can get the correct linkage system . Thank you in advance , Tom