Straight Eight engine removal
Hello,
It's been a while since I've done these but there is a procedure in the Buick manual that outlines how to do it. Believe it or not, the specified method is to remove the valve cover and lift from the rocker arm shaft. If you're just taking out the engine then lift from the middle. If you're taking the transmission with it you hook it back towards the firewall. The idea is to be able to find a balance point to allow you to lift the engine easily. In any event, this allows you to remove the engine and transmission without moving the rear end back.
As for rebuilding the transmission, I always check local shops first. If they actually rebuild transmissions then they can probably do the Dynaflow. However, many of the chain shops simply replace transmissions. They won't be able to help you.
Best of luck,
joetunick