Short version: One eave on a simple gable roof are giving me fits as far insulating and venting it. The intersection of raters from a low pitch roof, with old and new ceiling joists on top of a block wall makes it implausible to insulate properly and maintain any kind of vent. I’m thinking about running 50 three foot pieces of 1″ pipe from the soffit up under the deck and dense packing cellulose.

Long version: I am remodeling an early 1940’s 28 foot square cabin in NW Georgia. It has a simple gable roof. Walls are 6″ block.  
Ceiling and roof structure is 2×6 and 2×4 rough sawn pine and 1″ rough decking.  There are two layers of asphalt shingles. 70 years with no insulation and unimpeded circulation have preserved this structure very well.
There are 12 foot deep porches at either end, sharing the same ridge. There is a 14 foot addiction, slab on grade on one side. 
The original structure and the addition share a “new”, now asymmetrical, metal roof. 
Over the original structure, the bearing 2×6 ceiling joists and the 2×4 rafters sit on a single 2×4 rough top plate on top of the block. Joists and rafters are not spaced together, both on 26-32″ spacing. I’ve added new joists on 24″ for drywall as the original loaded joists have sagged over time. The result is like a box of french fries scattered along a very tight angle at the eaves. The notion of cutting anything to form a channel for ventilation is a nightmare. I’m framing 2×4 walls for insulation inside the block walls, making thing worse. The other side, meeting the addition, will be “normal” and I can provide lots of inlet on the gables ends under the porch roof.

I’m not into foam.

Any insight or references on how to insulate the ceiling properly and maintain venting. Criticisms or encouragement regarding runnig pipe to the soffits and packing cellulose? 

Thanks.