Most moulds of my acquaintance throw a Minié bullet of around 535gr - certainly the Lyman does that. But you need to measure the bore at the muzzle and subtract 1.5-2 thou to get a good fit, usually referred to as a 'thumbing-in' fit. The bullet should then load under the weight of the loading rod. The skirt needs to be fairly thin in order for the propellant gases to expand it into the grooves, and the bullet made of pure soft lead, in order to do just that. I've never heard of any notionally .577cal as small as .566", let alone .510". In my Parker-Hale Musketoon I shoot a .578" Minié over a plinking load of 55gr. Where your comment about the 'preferred size' originates, I have no idea.
If you give me your address I'll send you one of mine, made using my Lyman mould, and you can take it from there. No sizing is needed for a Minié - YOU do the sizing when you load it. Lubing is important though, and there are as many opinions about what to use as there are shooters. Me, I use a 60/40 Beeswax/Neats Foot oil mix - others will use Bore Butter [if they can stand the wintergreen smell].
Lyman, Palmetto, Rapine and Lee all make a suitable Minié bullet - I'm uncertain as to why those you have found make such a heavy version - I've never seen any that weighty - doesn't mean that there aren't any, just that I've never seen them.
Your load is in the middle of the 'sweet' range - anything between 60 and 68 gr is usually suitable out to the usual 800 yards-maximum range for the open-sighted two-bander in the MLAGB comps. The service load was 2.5 drams - 68.5gr, of fine rifle powder - about today's FFg or Swiss equivalent.
The rifling ROT is not set up for a patched ball, although there are some who have tried it with greater or lesser degree of success. IMO it defeats the object of having a gun designed to fire a particular type of bullet, and it would certainly be a waste of powder and lead at anything more than 50 yards, but that's just me talking, since I've never tried it - I just know a lot of people who have. Bear in mind that the patched ball will weigh considerably less than the bullet, right?
tac
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