Just wanted to have some opinions if the under wrap is black and the guide wrap is black as well will the Threadmaster hi-build cover any perfections?

With that combination, it will be very hard to see them.

The reason I ask is because I will be doing a double wrap of size A thread over guides and the transitions over each although because of it being size A the bumps are not high. I was thinking because of the high build it would end up smooth.

It will, for the most part, but on areas where you overwrapped threads and there are high threads, the finish will pull away and you may require a 2nd application. Just try not to have too many gaps or bumps. Finish can only do so much.

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If you do that combination right, it will look as if the guides are growing right out of the rod, the key is to be careful not to get any bubbles at all.

Use a black sharpie and color in the areas of the guide feet you prepped. That way, if you dont pack the thread really well, you should not have any silver peeking through the top wrap.

What Lou said.
It should look kinda cool. When I do an underwrap (not very often) and a guide wrap in the same color as the blank it just looks cool, kinda like the blank was made that way.

Thanks for the advice! I think what I have decided to do is use size D and make sure everything is wrapped perfect and packed solid.