The type H-6 is the only really relevent airborne radar set. 2000 built.
http://www.combinedfleet.com/radar.htm
Even though these could be deployed by late 1942, they were only widely installed by 1944. The Japanese did have an involved history with Radar and American sets were not the mover and shaker of Japanese thinking. There was even a fair amount of collusion with the German development.
H8K's should be the only real prime benefactor in SH4. In ASW, the Type H-6 appears as early as late 42' but on limited numbers of H8K, as the war progresses more aircraft are invested with this technology. This reflects the reality on the ground to a good level in SH4. RFB will soon have a very accurate account of this aspect of the war.