If I am understanding this your going to notch the post and the top rail so they fit flush with the top of the post with a half lap joint. Although this dosent fit the 1/2'' deep 3/4'' wide thing.

Anyway I would use tightbond 111 and #2 8 x 3'' ss torx head screws. J.

Thanks, John. It would be 1.5" deep on the top of the post for the top tail to set flush. The end of the top rail would not be notched. I was planning on using 2 screws.

Here is a link that might be useful: {{!gwi}}

Thanks, Sounds like I can go with the GRKs, then.

Here is a link that might be useful: GRK Stainless Fin/Trim

I forgot to ask about fastening of the cap rail. Given the above diagram, would I just screw upwards through the top rail, or should I somehow screw the cap rail to the post, as well? Thanks.

I would face fasten the cap rail with screws / Plugs to the posts as well as screw upwards thru the top rail. J.

That subrail under the cap in a cable rail installation, just works as a tensioner between posts. When you tighten the cable, the subrail keeps the posts from moving. I would think that any of your scenarios would be fine. The top cap is for decoration.

How often are you placing your posts? Something like 3' is the max. span of the cable, without it having too much flex and failing the 4" sphere rule.