71 198 slant 3 on tree

Just because it has four bolt holes on the one barrel side doesn't mean it won't work. If two of those slotted bolt holes will line up with the slant 6 bolt holes on the intake it will bolt on and work. My only worry would be how high they sit and whether the hood would close.
That worries me too . They said it won’t worl with a slant six . So o don’t know what some these guys are using and I’ve not done one in 14 years or more but I don’t remember it being this hard to just google and find one a s it worked perfect.