Do any of them taste similar to black eyed peas? I grow Roma II & regular green beans. It’s the black eyed pea taste I’m after
I'm gathering from your original post that you are mostly concerned with the flavor as snaps? Not having tasted the snaps of BEP, I'm unfamiliar with their flavor - but I'm assuming it is strong. While I have not seen that much variation between different cowpeas dry (other than texture), the flavor & texture of snaps is more variable, as is the tenderness of their hull. While I don't often cook the snaps of varieties bred for dry use, I usually sample a pod or two raw. Those with darker green pods seem to trend toward stronger flavor, while those with lighter green or purple pods (including most yardlong beans) tend to be crisper, sweeter, and slightly nutty. Both of the bush varieties mentioned above ("Yancheng Bush" and "Bush Sitao Var BS-3") fall in the latter category... and if cooked firmness is important, either would give you that.
I think that the type of cowpea/yardlong you are seeking will most likely be either a prostrate creeper, or pole variety. Have you ever tried any other types? "Pink Eye Purple Hull" is a creeper, but not excessively so... for me, vines 3-4' long. It is a pretty high yielder as a dry pea, and is fairly early.
If you wanted to try a pole variety, I would suggest either the black-seeded yardlong bean that I grow (which was probably sold as "Asparagus Bean") or the black-seeded pole cowpea that Russ sent me. The yardlong may give you the strong-flavored snaps I think you are seeking, and is
very early; but the dry seed is not noteworthy. The black-seeded pole cowpea Russ sent, on the other hand, has fairly good 10-11" snaps (though not as strongly flavored) and if let go to mature, and an
outstanding dry bean yield (it set a record cowpea yield for me). It may be the same as an heirloom named "Cow"; but since the O/S was lost & I can't verify that, I've named in "Black Angus".

Snaps in 1st photo: Black Angus left, Thailand Pole (which is outstanding but not very productive) right. 2nd photo is dry pods & seed of Black Angus.
If you feel adventurous & have room for a mass trial, I could send you a sampler of all the cowpeas I have, and the yardlongs which most closely match the description in your first post. Something is bound to get close, and you could have a lot of fun experimenting & taste-testing. Or if you only want varieties which do not need support (some of which may ramble 3-4') I could do that too.