On our
track race car we usually fill it up near to top line - not over it but not substantially lower. When it reaches the bottom line, we've had few cases that engine losses its oil pressure on track when first driving long corners and then straightening the car after a "small drifting". (it doesn't leak between engine block and sump, but it had to be installed with some loctite sealer, with only the paper gasket it leaked a bit - mexico case seems not to be milled as flat as gb sump)
We have CB 82 crankshaft, GB 2qt sump, schadek 30mm oil pump, fullflow, hacked up windage tray to clear cam lobes. Engine has 4 breather attachments on valve covers, oil filling tower and on gas pump block-off plate. We haven't discovered any power loss or gain according to oil level, but haven't dynoed the difference either.