Re: Running hot
Of course you can remove the side cover/s in situ. If yours is anything like the 6 I have done, you will be amazed at how much lower crud insolation lies there. This is the result of castings and years of oxidation thus the sludge is very fine particulate. Depending on how aggresivly you undertake the task, you will probably see damage to the diverter meant to send cooler water in an orientation, and possibly a deteriorated hose nipple.
Heat of course is at the top combustion area and why these little mighties get along so well over the years but purging the crud can only be a small blessing of salvation for the motor.