There are several threads you can seach for on this. DeadheadNM and I have posted to this which should clear things up some.
http://67-72chevytrucks.com/vboard/s....php?p=7017476
The conversion output shaft is the shortest version of the 700R4 and moving the engine forward a little makes everything work well. The colummn shifter works but there are issues getting a proper NSS lamps fuction as recall.