Of all the amps I've ever taken out of a chassis, the Mark IV was the HARDEST to get back in. My recommendation is to setup 2 stools or saw horses, flip the head upside down, and take the screws out the top while it's upside down. Same with putting it back together.
And ya, all you need is a screw driver. Also, probably should be moved to a different forum.
Best of luck!