I was at Pick and Pull in Fresno yesterday and saw a first gen Toyota pu with a dana 30 front end and a dana 20 transfer case. Obviously a 2WD conversion. I thought about grabbing the adapter from the tranny to the transfer but it was about 10" long and behind the old cast iron Toyota 4 speed. Didn't think it would be worth much.
I think the 400 was the better choice. Ive been told the 350 is better because its lower 1st gear, but its so negligible its not even worth mentioning. Have fun.....