Looking for my Duster's fender tag and original 225 engine.

While I understand why you're wanting "that" engine it isn't a 340 or hemi, etc so at the end of the day, having "that" engine won't make the car worth any more. On the peanut vs drool tube head deal again I get it .. but the peanut plug head wins for me if only because of having 6 less potential oil leaks vs a drool tube head.
Yes, that's a good point about fewer oil leaks on the peanut head. I'm not even sure why they went to the different head design in 1975.