It really depends upon the twist of the barrel. I do not know the twist of tbat barrel.
If you are 1:48, that is a good "average" twist that is easy to work with using PRB and conical.
REAL Conical are great. They have descending grooves that progressively get bigger, allowing a tight seal against most barrels. For the most part, REAL's will work well in most guns I know of.
When you choose a conical, you also must choose on what you want to put up with.
Rule of thumb: Tight fit means better accuracy.
But. . .
These tight fitting conical also have an disadvantage. . .you must swab between each shot, or you will have a very good chance of getting one stuck in your barrel when loading. . .. because of the "crud" inside of the barrel.
REAL's are tight fitting too. . .but you do NOT have to swab between shots at all. . .Another huge advantage for them. The disadvantage comes in accuracy. You must work up a load for them. I have about a 2" to 2 1/2" at 100 yards. Not bad for a REAL conical. But. . .with Sabots, you can probably MOA.
Method of choice for me:
1. How accurate do you want? a MUST MOA or close? Better use just about any Sabot type conical. Work up a load with it. Deal with the swabbing.
2. is 2.5 inches ok at 100 yards? maybe 3"? Maybe a REAL conical will work just fine with you. the Mold is about 26 dollars to your door, and you can cast all you want. Use wheel weights, goto Rotometal and buy bulk lead that is pure. (about 110 dollars for 50 pounds to your door).
the slower the twist, the less likely a conical will stablize enough to shoot accurately out of your gun.