The LE cases are shorter than a standard .45-70 case, therefore you can load longer bullets in a short throat. I loaded 405s in standard cases, and they are longer than the 325s and chambered fine. Dropped right in. If you want to load the flex tip bullet, call your die manufacturer and if you send them a bullet, they should send you a part to change in your bullet loading die to fit the bullet so you don't crush the tip. I know Lee does this for about 13 dollars including shipping.
I haven't loaded the FTXs yet, but I would think you could get close to or over 2000 fps with safe pressures.
Pete