its mahogany body with rosewood finger board. split coil setup. warm but not dark warm i would say.
You should be fine with this wood combination + the Emerald. From what feedback we've given in the forum, you're aware this pickup will feature the high end of the spectrum more than most pickups... and probably in a far more tasteful way than what's in there currently. The thing about Bare Knuckles is that whatever 'emphasis' is designed within the pickup's voicing - it's never obtuse. It's always tasteful. The only reason i've ever changed a BK pickup in my guitar is because they catered to different tastes than what i play - every single one has been brilliantly engineered.
Another thing to throw out there is the fact that the Emerald and Marshallhead bridge are very similar in terms of voicing, as i stated earlier in this thread. Both are brighter voiced, with the MH sounding a bit more aggressive/open, and the Emerald a bit more balanced/compressed. If you're matching up a similar sounding bridge pickup to it's neck counterpart, then that's another consideration towards making the decision towards Emerald. You should be fine, and perhaps even check with Tim/Ben @ BK too if you haven't already.. just for the hell of it. They know their stuff 
i'm aware of the high end. its that "tastefulness" you mention in that it might compliment well the marshallhead neck pup even with its high end. if its an ice-picky type high end, then no, it wont do in the balance i'm trying to achieve. if not, from what i read and contemplate from the forum, the Abraxas would the other choice. or buy both but watching my pennies too.
i am indeed wanting to match up well with the marshallhead neck pup as i really like it and no one that has listened to it in this guitar says othewise.
i don't want to beat a dead horse any deader than it already is, and you guys have helped tremendously with your advice and time.
i'll email Tim and see what he thinks. for now, either emerald or abraxas.
thanks