I agree with Beater - the general layout is consistent with Chevy 216. The external oil line (passing back into and through the block) to feed the rocker arms is a tell . . . as is the location for the oil pressure sender . . .
But the head is sort of odd. The short side head bolts typically sit in cast nooks surrounded by the top side water jacket - and the water temp sender hole is typically over the rear intake port:
On the engine in the pumper the the short head bolts are on what looks like a flat - with a flat casting behind. And the water water temp sender hole is way back over the last exhaust port in a bulge that looks more like a boss(plugged).
At the front it appears that the head extends beyond the valve cover . . . curious . . . but I still vote Chevy.
Not sure what that tube running from the exhaust manifold to the dash would be for? A hand warmer?
regards,
stock49