There is a big difference between the start-up costs of buying a Harman Mk II and buying a coal boiler.. UglySquirel currently has a wood stove set up, so the install of a Mark II is pretty simple, swap the stoves, clean the chimney of creosote, add a barometric damper to the flue pipe and your're done..Too bad you can't find a good used Mark II for a reasonable price..
BUT, If you really want the best, the above statements about a coal boiler are 100% right... Contact your Harman dealer about their VF3000 boiler.. It is a nice unit, Or look at a Keystoker Kaa2, both are about the same BTU output,, just about right for a newer insulated house like yours..
The install will be more complicated.. but the ultimate payback is much better,, you can use the boiler all year, for DHW, and eliminate hot/cold rooms because your baseboard heat will be distributing the heat.. Something to consider with $4.00/gal heating oil.