Lee, this is not an uncommon problem. The shoes can fuse to the drums when they sit for extended periods. The shoes fail to retract and then they can get caught up inside the drum on the lip (which will be turned down when they are turned. Are your drums not budging (frozen drum), or are they coming a little but you can feel the shoe springs pulling them back (frozen shoes to drum)?
Since you have already removed the full floating axels, and tapped lightly all around the drum with a dead blow hammer to try to break any bond the shoes have on the drums, squirt some rust buster in the adjuster hole every day and use the straw that comes with it (or the carb cleaner cans) and be patient. It likely either the adjuster is not retracting or the shoes are fused to the drums. A drum puller will need a block or plate over the axel hole to pull against, but will help get this job going some. Those drums are wicked hard (Bostonese) to find so be careful to preserve them in tact as you get more and more frustrated with them not coming off. I've found that using a liquid wrench over a week or so eventually will free them up for removal but patience is a virtue.
Those flatheads do not have to come out to remove the drums as far as I remember, but I could be wrong. I am better with GMC than Chevy :confused: but I think they are the same drum in this case.
