new studio designe help need

Hi there! Trying to make cheapest decision in building recording studio. Room1 L:4m, W:3,1m, H:3,3 (entrance) Room2 L:4m, W:2,5m, H:3,3 I'm not sure which one use for CR. There is no worries about noise cous there is no neighbors. I'm planing to flush mounting YAMAHA HS-80M. is it good idea? Budget is tight <300$