If you do decide to replace some or all of the clapboards, check out these two mills:
http://www.woodsiding.com/ http://www.wardclapboard.com/index.html They both produce true vertical grain pine and spruce clapboards the old fashioned way: on a circular saw mill that slices the logs into pie-shaped wedges. Great folks to deal with.
Good luck,
Dave in Padanaram
