It looks like its been decided against the big stroking for this A15 anyway, but its still intresting in theory.
I think stroker cranks on street engines, eg holden 308's are unreliable enough, cost $000's and too often go bang. the additional piston speed of adding 5-6mm to stroke would mean a lot of work would need to go into balancing etc to have the same redline achievable, and in a race setting where it needs to be constantly up there even more risky.
I think to do it u would be increasin bottom end to midrange torque by greast gobs but nothing much up top end, and for racing its mostly up there all the time.