Whilst your on the point of mixing and matchingI"ve often wondered about this combination.
EJ25 block for maximum bore capacity
EJ20 crank , shorter stroke better rpm capacity
custom long rods - improve rod ratio by having the taller ej25 block and the short stroke ej20 crank. The long rod combination improves rpm capacity.
Overall capacity will still be close to 2.5L (about 2.4L I think).
I really dont think the strength of the block is an issue after all turbo motors are putting out much higher hp's than n/a would ever be capable of and whens the last time you heard of a block failing?