HARRY - A torque wrench rated only 150-180 inch pounds would be only 12-1/2 to 15 foot pounds which would probably be a 1/4" drive wrench. Company I used to work for had small screws they torqued to 4 INCH-Pounds, but used air wrenches for them.
Just so it's clear. converting from foot-pounds to inch pounds, you multiply the number by twelve (12). And to convert from inch-pounds to foot pounds you divide the number by twelve (12). I've also seen torque spec's rated in Inch-Ounces, but there's nothing on a Kohler with that rating. That's REALLY not very tight.
MIKE P.- Can't really say if your may have the head bolts too tight or too loose. Sears/Craftsman doesn't appear to offer my 3/8" bending beam torque wrench anymore, Mine is calibrated in inch pounds, zero to 600 inch-pounds, which would be 50#/ft. They only sell two now, calibrated zero to 75 #/ft, one 16 inches long for $13 and the other 20 inches long for $27. Either one would be fine for Kohler final assembly.
You still need your big torque wrench for the nut on the flywheel.
On parts like head bolts, used threads, I chase the threads in the block with a new or really good tap and blow out the holes with compressed air and wire brush the whole bolt or stud. New parts like conn rods I spin the nuts on by hand and make sure they spin free, if they catch, I chase the threads on the bolts with a die and try them again, if they still catch, I chase the threads in the nut with a tap. On used parts like head bolts into the block I also test them by installing them finger tight first too.
I always tighten the fastener in three steps, like in the case of a Kohler head or conn rod, where the spec in 25-30 ft pounds, 300 to 360 inch-pounds, I'll do 10 ft-pounds, or 100 inch pounds, then 20 ft-pounds or 200 inch pounds, then finally, 30 ft-pounds, or 350 inch pounds.
Most manuals don't specify to tighten in steps, but some do and it's a good idea to do it all the time.