The torque is going to have the effect of rolling you to the left in the F4U. It makes turning left a bit easier, and turning to the right a bit more difficult.
If you try to roll right at the top of a rope while at that stalling point, you'll probably get "stuck", since the control surfaces are fighting the torque, and things seem to "equal out". On the other hand, if you try to roll left at that point, the combination of torque and control surfaces may toss you into a wicked snap roll to the left, and you may have a rough time regaining control quick enough to keep you happy.
You may find reversing is a bit easier at the top if you don't let yourself get quite so slow, and if you use a notch or two of flaps to pull back over onto your back at the top. As soon as my nose drops below the horizon though I'm bringing my flaps back up. If I'm going up at an angle, I'll roll 180 onto my back, pop a notch or two of flaps, and swing my nose back down. Just avoid that rolling while so slow. Rudder can be a mixed blessing too. It's got the best rudder in the game (IMO)(which is attached to the best plane, BTW...). That can allow you to do some great things with it, but it can also get you into some serious trouble very quickly.
I don't like getting super slow at the top of a rope, since it leaves me few options and is easy to get momentarily "stuck" like that. If you opponent is drawing into guns range at that point you're dead. I'm generally beginning my reversal while still flying at about 150mph, or maybe slightly less. If I can't do a successful rope with a reversal at that speed, I abandon the rope and change tactics, right now!