318 Duster Rebuild - pros and cons of keeping matching numbers
Unless you have a good local shop I'd be super wary of sending an engine off somewhere to be rebuilt. Maybe consider keeping your original engine stored away and put a crate magnum in its place. Looks like ATK will sell you a 350HP 360 for $4,100.00
ATK HP113 Chrysler 360 Magnum Engine 350HP I really doubt you could get your 318 rebuilt for less and if you did it still wont have 350HP.