I've cooked shoulder clods twice before (from Smart & Final). They've come out quite well for the most part. But, I have never cooked a shoulder clod past medium well.
Like a pork shoulder, it's got many different muscles so there are some darker meat (i.e., tougher muscles/sections that need longer cooking to get really tender) and some lighter meat (i.e. softer muscles/sections that are good on the rarer side that being fully cooked). I actually remember preferring the muscles that were well cooked and tender; the core was still very medium even though the outer meat was well cooked. (If some parts are cooked to around medium, they may need to be to be sliced to get the best texture; some parts may be tough.)
Again, I'm not too sure about how it will turn out if it's fully cooked through (I haven't done that yet), but one thing I did notice is that it's significantly less fatty than a pork shoulder, and certain parts of the exterior were a little dry. It doesn't have the collagen of a brisket so it's not going to have that soft mouthfeel of a well cooked brisket.
If I were to do it again, I would still cook it to medium, but finish the cooking by wrapping it in foil and give it PLENTY of time to rest so that the juices will redistribute through the entire shoulder so it's consistently cooked throughout.
For me, beef needs less wood and more charcoal. Beef, IME, can get acrid tasting when smoked with too much wood. I also prefer a combo of oak and hickory, with more oak, for wood.
For rubs, I tend to prefer either a simple pepper based barbecue rub (salt, black pepper, cayenne, garlic and onion powder, thyme - no sugar) or a prime rib type of rub when cooking beef, I've made various rubs that have a combo of salt, black pepper, white pepper, paprika, little cayenne, thyme, some garlic and onion powder, coriander and rosemary (being very judicious with this last ingredient). I don't like using rubs with sugar on beef because, to me, they can produce bitter/burnt/acrid flavors because, from what I'm assuming, is the long cooking time.
Also, if you want to ensure that you have enough charcoal for that cook, bring the clod out of the fridge a few hours early keeping it covered, and let it rise in temp a little. That'll shave some time off your cook.
P.S. - there are several threads on various forums about cooking clod. Good luck!