Sorry guys...didnt think of taking any progress pics of the dash rebuild. I know, I know....I should have done that to help the fellow square builders out there.
Basically, here is what I did (without pics).
1) I chipped away the loose plastic by hand and vacuumed out all loose foam
2) filled in any and all cracks, voids and holes including the speaker holes with body filler a.k.a. bondo. I attached cardboard to the underside of the dash using some self tapping screws to temporarily hold the cardboard in place until the bondo was dry.
3) once the bondo was dry, I sanded down and rough edges and high spots with 80 grit sand paper on a random orbit palm sander so that they would be flush to
the top of the remaining dash vinyl surface.
4) I used some high tack upholstery spray adhesive to attach the tweed fabric. I sprayed the dash, let it set up for 5 mins, then sprayed the backside of the fabric, waited 5 mins, then carefully stretched and pressed the fabric to the dashpad surface. The tricky part is keeping your hands away from the adhesive. Once attached and dry, it won't come off very easily. Patience is key. I have done his once before on another truck years ago with great success. The only difference was the other dash was intact and didnt need rebuilt. I used tweed because it easily contours to the curves, its inexpensive and since there is no real pattern in the stiching, its relatively easy to adhere to almost any surface. My headliner and door panels have also been covered.