Eventually found some numbers, The JAP engine has what appears to be 2AV 85976 pressed into the cowling, although the V could be a U. According to a JAP dating list I found this makes it 1956 or 1943. I’m not sure when they began making 2A engines but since this one had a recoil starter I am guessing it is probably 1956.
Taking a closer look at all the JP mower pictures I can find I now think this could be an early style Maxees push mower which someone has put an engine on. All I have found so far on it are three letters G V E inscriber on the sideplate near the back roller.