Hood Building Questions

Im gonna get a plenum made to fit top of my mark II and connect a 6 inch pipe to it and run to my centeral return box when i turn fan on for centeral heat system it will suck heat off top of stove through hvac filter and into floor vents all over house .how high should i make plenum off of stove and should i make plenum go down over sides of stove ....any suggestions or pics

To get more heat out of the stove, side jackets would help a lot, make sure you furnance heater is not too powerful, it may cool down too much with the air flow. Not sure if it is adjustable or not?

6" may be a bit small, if you can fit 8" might be better, you can alway adapt down easily.

Look in the "Best of" Pitures of Your Stove Thread, many of us have build their own heat jackets or plenums of various forms.
Pictures of your stove