hey man. i just had my dash completely out to replace the heater box, yes, it is a big time consuming job. i havnt done a heater core on these, but the way the dash tips forward, i cant see why you couldnt do it without pulling the whole dash. theres the 5 screws at the windshield, few on the bottom and the whole dash tips forward. removing the steering column alows its to tilt more, but should be ok with it in.
i think i seen a bunch of vid's on youtube for this, check there to see what your getting yourself into.
heavy.