Hi ya.
Well, the original bullets and cartridges for the Enfield where Pritchet bullets of various calibres. See here if you're interested:
http://full-bore.co.uk/viewtopic.php?f=10&t=5164
A bit of shameless posting of my thread.
However, as the Parker Hales are modern repro you're find that they're probably going to be around .58"-ish calibre. Everyone I've know who owned or owns one, simply buys or casts U.S. "Springfield-" type minie-ball bullets, which are designed to fit into a .58" calibre Springfield.
These will certainly sort you out for 30 yards, though you'll be very high on target.
For a 200 yard powder charge, I would try at 55 grains* and go up from there. You'll probably find that you only need around 60 grains.
Do you know what type of powder you're looking to get?
*Real Black Powder.