Hi folks, while taking apart my 1981 evinrude 235 of course bolts broke off. 2 on the starboard side I drilled out and retapped with difficulty. But the port side has 10 broken studs and I don't feel like all that work. E-bay has port heads for sale cheap enough but I was under the impression the serial #s have to match the old head. Is this true? How important is matching castings on the port head? Wouldn't the head gasket fill in any casting mis-matches? Thanks in advance for any replies.