[Lynn Eades]

A little trick I saw used to free up astuck engine, might help here.
The guy had a siezed motor (fronm sitting, head off exposed to the elements) What he did was to pour a quantity of diesel on the pistons, and set fire to it. It burned with a weak flame, but over time the localised heat expanded things in relation to each other. the result being the motor freed up nicely.
These v8's are notorious for sticking the guides in the block pretty tight, and often its the motors that have sat around, that are the worst.
If you attack without caution you may well end up breaking someone elses special tool, or part of your motor.
If your motor is out, try setting a fire in your valley around the guide you wish to remove, and let it burn until the diesel is gone(you will have to roll the motor to a suitable angle, and maybe block the odd hole)
The guide does have to go down (in) a little to allow the removal of the circlip, before the assembly.
Time / money, spent getting the valves right is worth it, and is one of the main reasons why these motors are expensive to rebuild