Easiest to build attys for the REO are the RM2s. They also offer superior flavor and excellent vapor density. I use a non-LP Grand daily with a non-LP RM2... and another non-LP Grand with an RM3 Dual Coil version. My next REO will be an LP and I'll get an LP RM2 with it to start out with.
The RM2 is easy to build and really does offer excellent vapor density, excellent flavor, and low maintenance. It's one of the easiest devices to recommend for a REO.
I'm not sure this is very instructive. Let's get rid of a few acronyms first. LP = low profile - it means your Reo has been milled down to accept anything on top, yes, even your tank atties. The earlier versions of Reos had a catchcup that only atties of 14mm or less would fit in.
All the atties sold on the Reosmods website are called RM(number). The RM2 is a modified Triangle atty and a RM4 is an Atomic, again modified to bottom feed. So it goes.
You do want a bottom feeding atty on a Reo, because putting a tank on it, while possible is really desert island stuff.
Get a LP Grand - no, it's not that big, and a RM2, because it's the easiest thing to build coils on ever.
i never tried to measure vapor density, so i'm clueless as far as that goes.
Post pictures when you get it and see you around!
T