Ditch the intake and carb, youve got an essentially stock intake and a very hard to tune carb.

Also who knows what cam is in it? Without knowing you're probably just playing guessing games. In my experience when someone doesnt know whats been done to an engine they either know and dont want to say or whoever they got it from told them that because they knew and didn't want to say. It was probably rebuilt with a cheap rebuild kit which usually has low compression pistons.