It was more than likely side mounted perhaps similar to the 63-66 years. they had side perches that were on either side within the frame rails. 2 wheel drives all had that large frt crossmember for the frt end. 4 x 4's don't have that so have to mount differently.
other than that if you I6 mounted on that 3" round pipe ,your 283 may mount there as well, utilizing the same frt mounting that was used on the 265 engs in 55-56 cars and I believe l/duty trucks up to 59. they used those 2 vertical 3/8 threaded holes on either side of the frt crank pulley
ron
