[grumpyunk]

Any CR design should be 'dynamic', cutting out when rpms get higher than xxx. With all the parts static, a leakdown test should be doable without any problem.
If you are at TDC, and have a CR leaking out the gases... it would be counter-productive at all rpms though less noticeable at high rpms. Most CR mechanisms use a bump on a cam lobe, or a movable interruptor, neither of which should be doing anything at static TDC.
Please explain how the CR works such that it would make a leakdown test unpossible? I have no mental picture that would explain.
Did you get an el-cheapo lipstick(?) camera to connect to a laptop PC and shove down a spark plug hole? They are less than $15 on DaRiver or DaBay. I have used one to inspect cylinder walls. I would be concerned that the lean condition did some damage to the piston crown. It MAY have eroded some of the metal around the perimeter. I have seen that happen on engines that got too hot. Most were air cooled, which seems to indicate they are more susceptible, but I wouldn't make any bets.
One last thought is that extra fuel that makes its way to a catalytic converter can cause the converter to glow cherry red. You would get a lot of sparkage if that occurred while turning 9k.

tom