I haven't used 500 count for anything. 400 would probably be a good start. Those resistances are in the ball park of what i have been building as well. If you have a wick hole greater than or equal to 3mm--28 g kan is nice and sturdy.
On the attys that i currently have in rotation--the largest wick hole fits a 2.5mm jig. I use drill bits to wind a coil on the atty. 32g kan and 34g kan for my aga titaniums(2.0mm wick hole). Aga
devices are great, i love them. But those little jam nuts are often stripped out of the box. Hardware stores carry stainless steel hex nuts. Metric 2.0mm hex nuts work perfectly on aga devices--and hold the pos lead wire.
32g and 34g wire are a pain to learn. But here's the thing--i haven't even had to clean the
coils of my aga gennys for almost two months. And i have used them quite heavily. I like the flavour that i get with builds with fine gauge wire.
Solid wicks, but rolled not super tight. I oxidize, so that my coil will last longer. I seem to damage my wires and burn holes in the mesh if i attempt the pulse method.
Good luck!!!