Sounds like you have the right idea in mind. But I think you were misinformed somewhere, this is a common, annoying mistake...
Snaffles can not have shanks, if the bit is jointed and shanked it's simply a jointed curb. Snaffles must have rings of some variety and NO leverage.
Personally I avoid any jointed leverage bit, I just find them too be too much. If you're looking to start your horse with the mildest mouth piece you should look into double jointed snaffles (with rings). Bits like a French link or lozenge style bits like a KK ultra.
The reason I prefer the double jointed bits is because they are designed to be comfortably carried by a horse and when pressure is applied it won't hit the roof of the horse's mouth, like a single jointed bit.
I prefer full cheek or big D ring snaffles for horses still learning or moving over from a bitless bridle as it adds pressure on their cheeks/lips to help push the head, not just pull - it also hold the bit in the correct position in their mouth without much movement. But loose rings are nice for horses who carry the bit comfortably or tend to lean on the bit.
If you feel you need a leverage bit for some reason look into curbs with solid mouth pieces, either mullened out away from the tongue or with a small-medium port, depending on the horse's tongue relief preferences. The shorter the shanks in relation to the purchase of the bit, the milder it is - and vice versa (long shanks with short purchase make harsher bits). I like Sweetwater Butterfly bits best - but that's my preference.
ETA: About getting the horse used to the bit. Make sure when you lunge the line is attached to a halter, not the bit, that puts unnecessary pressure/pain on the bit and can teach a horse to ignore or avoid pressure/contact on the bit.
If you want the horse to neck rein, just try neck reining them from the ground in the new bit, if they respond well, hop on. If not I'd switch them into a true snaffle (no leverage), practice giving to direct pressure from the ground. When giving well to that I'd hop on, practice direct reining with a neck-rein pre-cue. But a western trainer may have better guidance for you than that.
Last edited by PunksTank; 03-11-2013 at 10:29 PM.