Welcome to the Case forum Mcloud. Doth tractors ypu mentioned are good prospects. There where however fewer VAO's produced. From 1942-1955 there were a total of 6925 VAO's mades, 1817 units were produced in 1947. There was a total of 15031 VAI's made in the same time frame. There was 2934 VAI's produced in 1948 alone. That was the highest number produced in one year. 1947 was also the highest production year for the VAO.
Like most of the older Case's one can get lots of money tied up into engine parts. If the tractors run that sounds like a very fair price. Also check sheetmetal, tires and for cracks in the engine block and the transmission and rearend housing. Good luck with them and be sure to post some pictures if you get them.
caseman-d