Later head on early block

So after I got this new car, I pulled the head to check out the cylinders (engine had been sitting, rings lightly stuck to the bores), but it turns out the head on the 3 main block is an "L" head from a '72-'74. There don't appear to be any valve reliefs cut into the block. Are the exhaust valves the same size as the early heads and are they in the same location with respect to the cylinder walls? I assume they aren't, hence the need for reliefs, but I would like to hear it from someone who knows. Or is it the larger intake valve that is a problem?
Thanks.

Jake,

Check out Sean Brown's article at flowspeed: http://www.flowspeed.com/cylinder-ident.htm

Only the intake valve is bigger.