Turning that whole thing around, has anyone ever drawn a super-heavy Federation starship equipped with only the more widely used two nacelles, but those two engines being larger? (In other words, one possible example might be a ship like the Federation class, but with only two super-sized nacelles) Wasn't there a variant of the TOS-style nacelles drawn in fanon that simply took the nacelles of the Constitution-class and made them longer? I have to admit I perfer the symmetry of two-nacelle designs.
Maybe another approach to this is to question what the term "dreadnought" means in the context of a Federation starship anyway. Fanon designs have been conjuring up progressively bigger and more heavily equipped super-sized battleships dating back to the 1970's, and then DEEP SPACE NINE came along and the deadliest Federation warship ever made turned out to be that dinky little Defiant.
Don't get me wrong, though. If you want to look at uber-heavy battlewagon designs, Vance's "Couer De Leon" is probably the most elaborate.