I've had pretty good luck with a plain ol' clunk tank and muffler pressure, at least with the 46LA on a 54 ounce profile Twister (yes -- way overweight).
I'd recommend starting with an APC 11.5 x 4; compare that with an APC 11 x 4 and an APC 12.25 x 3.75. At that weight, you'll probably like the 11.5 x 4 best. Whatever you do, spend some time swapping props and finding the best one -- every plane & engine has a prop that it's happiest with, and it's different each time. So -- experiment.
Get some nylon net -- pantyhose is supposed to work; I prefer the fine mesh net they wrap flowers with. Get some O-rings that are the right size to hold the net onto the venturi. Go to the field with a little bag with O-rings and squares of net about 1 1/4". You can tune the engine power with squares of net held over the venturi with O-rings -- basically, they're a quick and easy venturi restrictor.
You want to set the engine up so that it's in a wet two-stroke through the whole flight. Without modifications that kill power, on that size plane, the 46LA does not want to go into a four stroke. For a first cut with those props, I'd launch at around 9500 RPM. If the plane "runs away" (suddenly goes into a mode where it's screaming fast and pulling your arm out of its socket), then pile on more mesh and lean it out. If the plane doesn't have enough power in the overheads and the tops of maneuvers, remove mesh and richen it up. If there's no happy medium on a 52 ounce plane, an 46LA, and one of those props, then something's wrong with the motor.
If you have someone to help you trim, follow their recommendations. If not, search out Paul Walker's trim articles and follow them. Speed is a good band-aid for poor trim, so start out flying fast (5, 5.2 second laps on 67' lines). Line length is a good band-aid for a heavy plane -- I'd suggest starting at about 67 feet handle-to-canopy (i.e., about 65' eyelet-to-eyelet).
My goal as I trim a plane is to get the trim good enough that I can drop the speed and still retain control, and so the plane is mostly flying itself. The slower the plane is, the more time you have to respond to it. Ideally, you flog the trimming to the point where the plane mostly flies itself, and you're just suggesting a course of action via the handle. If you're having to constantly issue course corrections just to keep it on the straight and level, you're doing something wrong.