That dash looks familiar. I used to have a 97 bluebird tc2000 40ft, Allison 545 and Cummins 12v 5.9. You could floor that thing going up and down the hills on each side of the Mississippi here in Iowa and the temp wouldn't budge. That stock 12v couldn't output enough power to overheat the 545 going up any incline... Traffic behind me would get mad as we did it at 25 mph though, haha. Even on the flat ground of I-80 between Davenport and Iowa City it'd max out at 57 mph... 59 with a tail wind.
Once I actually got somewhat stuck in Port Byron, IL. Coming out of "downtown" on the riverfront you've got a straight shot up the hill to the highway, where there's a stop sign. If you stop at the sign, the slope is tall enough you can't get the wheels turning, so you have to blow the stop sign. But it's a busy highway so if you hit the top and there's traffic, you have to stop, back about about a mile down the hill, and hit it again. I did that for half an hour once...