The Raider and Trooper are similar in style and intent, but are not the same truck. I don't believe any of the engine parts are specifically interchangable, and almost certainly not an application specific part such as a cylinder head.

I do not know of any other nameplate that was applied to a first generation Trooper. Acura marketed a version of the second generation, but I don't think that's what you're looking at. What I believe you are thinking of is the Dodge Raider and Misubishi Montero were the same truck in the early generations.

I'm afraid the only other sources you're going to find for that head will be Isuzu trucks of some stripe or another.

James