the sk5151 can be replaced with an ir6220 (5151’s are getting increasingly harder to find in bulk), you just need to swap legs 1 and 5. DO NOT use a sk5050.
when you add your write up on chipping please add a section about adding a datalogging cable, and we will stick this in the tech write up section.
Edit:
and here, this should also be helpful
http://www.zer0daze.com/stuff/Common%20ECU%20Parts%20List%20From%20Digikey.xls