Looks good.
Would you mind sharing your experience with it after this period of usage?
If you are satisfied with it I might try to do the same thing and that way get a flat pedal power meter for a reasonable price.
I was thinking on getting just the left SHI model and use the original right PD-GR500 pedal as it is.
Given that you have to cut the left pedal making it shorter (if I understand it correctly) it would somehow compensate the difference in length after the SHI installation, right?