if you add up all the work (and less than optimum results) of trying to do this with the engine in the truck - you may just want to consider removing the engine and taking it out of your garage to clean, prep, and paint.
it sounds like a big task, but much of that is mental... its really not a huge deal in an old truck with few connections to the motor and lots of room to work. just another perspective.
I took mine out and with 4X4s set it on a flat cart bought at auction. It is much easier to clean. I used lots of wire brushing and scraping one section at a time. I used lacquer thinner a lot cheaper just be careful and use gloves and open air. Use only a hand wire brush if using it. I used card board, drip pans and masking painters paper to catch any stray material.
