Re: Recommended BBC timing
This may give you some insight on the timing that BBC's often like.
For 540ci BBC Street/Strip motors, 37* total is fairly common. That's what mine likes, and so do quite a few others that I'm familiar with. These motors run solid roller cams with around 265* to 275* duration at .050, and around 11 to 1 compression. They also generally like about as much initial timing as your distributor can muster. Mine is very happy with 30* initial, then another 7* centrifugal, for that total of 37*. With that tune-up, it starts immediately, the throttle response is surprisingly crisp and quick for a big motor, and it made 710 ft lbs and 781 hp on the dyno. Less initial can make these big motors a bit lazy with throttle response.
A note on not using too much initial:
As I said above, my motor and others tend to like a lot of initial timing. But you can end up with too much of a good thing as well. If I give mine too much more than 30* initial, it will on occasion, if conditions are just right, think about kicking back. It hasn't quite kicked back yet, but it will out of the blue try to turn over slow like it has way higher compression. And this is with a good Optima battery and a good high torque mini starter. As long as I keep it to no more than 30* initial, then its always as happy as a clam.