The 983, being larger, with no hopper, would definitely be better suited for burning wood. The 8in. to 6in. flue reduction could be done but may result in unsatisfactory draft and poor performance. The 503 could burn wood just like any other hand fired coal stove, once the hopper was removed, but would be less than optimal due to its size. The 983 is rated for 3000 sq ft. The 503 is rated for 2500 sq ft. I would rather run a bigger stove at a lower temp than try to max out a smaller stove, and maybe still not be able to heat the house, especially on colder days.
Being that neither stove is quite right for the situation, I would recommend (can anyone see it coming) a Baker!!!
In my not so humble opinion, the best hand fired, blower stoves on the market!!!