Ok thanks!

If you are just using the rope to lower something or hold something in place you should use a static rope and not a dynamic. You only want to use dynamic rope to help absorb a fall.

I predict 4 pages of "if you have to ask you shouldn't be doing this". Not from me, that's just MP's favorite answer to this sort of question.

I know this isn't what you asked for but it's important: is this on public land? If so, you should probably contact the land management agency and defer to them. In many cases, they want to be the ones to deal with the problem, not you.

If the above doesn't apply in this situation and you are the person who is supposed to be dealing with this issue:

It shouldn't matter whether you are using a static or dynamic rope because you shouldn't be loading the rope dynamically. Connect the rock to a rope and then just trundling normally it is a bad idea.

The goal is to have a controlled lowering of the rock. In this case the deciding factor for the rope should be strength. Is the rope strong enough to hold the boulder with a reasonable margin of safety?

If not, then get a thicker, stronger rope. Static ropes tend to be made of different materials and tend to have a higher breaking strength for the equivelent diameter or weight, but in this kind of situation, rope weight shouldn't very high on the priority list so just get a thicker rope if there is any doubt. 

Close the trail while you put a bolt in it and lower it down. Or, station people to block the trail and chuck it when there's no one below. What you're describing sounds like a recipe for the death of an innocent bystander, so maybe don't develop the cliff.

Chris, if your going to lower something heavy like a big block, realize that a device like a grigri will likely not have enough friction to control the descent of the block safely. Did you delete the OP? Can you PM me to talk about this?

Jon Rhoderick wrote:

Chris, if your going to lower something heavy like a big block, realize that a device like a grigri will likely not have enough friction to control the descent of the block safely. Did you delete the OP? Can you PM me to talk about this?

This. A Super munter would probably work but you should probably do more research into this part. The fact that you changed the original post so quickly with so many questions unanswered is a tad bit alarming.