Just be careful, as the machining limit for both the ka24 and ca20 heads is 0.2mm. I worked the new CR out a while ago, i think it gave an increase of about 0.1, so for the ca20, the CR would go from 8.5:1 to 8.6:1.
Don't shave it more than the machining limit, just to be on the safe side.
Weren't any ka heads laying around hey? Â
I'll be attacking my throttle body and plenum again this weekend....
EDIT: Using that supplied calculator, for the KA heads shaved 0.2mm the CR would go up to 8.75:1