Ok, I need some clarification. Did you swap the 305 ENGINE for the Corvette 350, or the 700 trans for a 350? If you swapped engines, unless the shifter adjustment was moved while the engine was out and the trans was hanging, the engine swap shouldn’t matter. The shifting characteristics could have changed if the TV cable isn’t adjusted the same or adjusted correctly.
If you disconnect the shifter rod from the column to the trans, will both the column and the trans move they the entire range of movement smoothly and without binding? If not, that needs to be corrected before going further.
If you swapped the 700 for a 350 trans, the steering column shifter has different “gates” with specific detents for each gear.
The 700 column will probably work ok, you just need to be sure that it will line up close enough in park, reverse, and drive. Your probably not going to be able to get the detents to line up with every gear, and the neutral safety switch may not work in both park and neutral since the distance between each gear is a little different.