Personally, I believe the 25-20 WCF to be the best choice for Field Pistol. Congratulations on a wise move.
Lil' Gun is probably a good choice, but I have no personal experience with it. My load is Remington 7 1/2 primers, Hornady 75 grain bullet, and 6 grains of N-340. This is a very accurate and mild load.
Let us know if you come up with a good Lil' Gun load.
Best of luck,
Steve W.