I think its a 472 or a 500

I picked up a running big block last night.
Its got the firing order of 15634278 (cast into the rear of the intake)

And on the exhaust manifold it has stamped;
1609255-3

I think that narrowed it down to a cadillac 472 or 500.
Anybody have any expereince with these? Can anybody point me to pinpointing which one it is?

Is the crank flange where the flywheel bolts on scalloped or round at it's outer diameter? These look like little half moon cut-outs between flywheel bolt holes. Scalloped crank flange is 425. Scalloped crank flange with tiny exhaust manifolds can be a 368. Round outer diameter = 472 or 500.

472/500 has a screw in fitting on the rear of the passenger side cylinder head for the heater hose. This fitting sticks straight out. 425 has a pressed in stamped steel right angle hose fitting there.

Exhaust manifold casting numbers do not vary between 472 and 500 C.I.

Sure way is to use a measuring stick down 1 spark plug hole. Turn engine over by hand and carefully measure distance between bottom and top dead center.
While you are there, shine a bright light down the spark plug hole to see if the top of the piston is dished or not. This will help determine the year. Does it have an EGR valve?

A picture might shed some light too.