To me, the 77 barlow is an elegant knife. It's beefy enough to handle tough tasks, for sure, but the bolster stamp and overall feel of the knife is very elegant. It's a dressy knife, for a barlow. Things like brass bolsters and scratted bone are cool, but I don't think that they're right for this knife. For covers, the red sawcut, african blackwood, and ivory bone all fit perfectly. Horn like in Harry's barlows would be great as well. Feathered buffalo horn would work. OD micarta or osage orange wood, not so much.
As for blades, I have to agree with Tim in that caplifters have been done to death, and they really don't fit with this knife anyways. A caplifter on a 77 barlow would feel very gimmicky to me. I really like the combination of the spear and coping blades on the last run. My biggest criticism, and it's really a small one, is that I wish the spear was pinchable. It seems like it would have been very easy to take a little bit off of the coping or shorten the swedge on the spear a little, which would have made it very easy to pinch open the spear. To avoid repeats, I'd like to see a reversal of these blades and have a sheepsfoot/wharncliffe main with a pen secondary. Ideally, a wharncliffe like the first run you made, except with the swedge ending before the nail nick instead of after it. This would allow for a nice deep nail nick and would allow the main blade to be pinched open. A healthy pen secondary, about the same length as the coping on the last run, would compliment this blade perfectly.
No matter what you end up going with I'm really glad to hear that you're planning another run of these barlows. They are my favorite line that GEC is putting out, and I'm excited to see what comes next.