not to be disrespectfully but it doesnt sound like u know much about engins (not saying i know evertything about them) but if u dont know what those things (air/fuel and exhaust valves) are and how to pull the pistons out should u be putting a 4t apart u probably have to drop the crank out to get the piston to come out and i would say that head needs replasing (doesnt look useable) changng motor is going to be the cheapest option in my opinion.
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94 mc28 SE