No you absolutely do not need to touch the combustion chamber to match a 4g64. As for the head gasket, get one for a 4g63 if you are using a 4g63 head...think about it, you don't need oil passages through the head gasket where there are no holes on a 4g63 head for oil to pass through. If you are using a 4g63 head, a 4g63 head gasket is going to have all of the holes you need for it. The 4g64 is going to mount up just like a 2g motor, so as long as you can do one, you can do the other. If your really that worried about it...go with a 2.3...it's not like you can't squeeze enough power out of that to merit the need for a 2.4L. Even a solid 2.0 is a damn good motor so I wouldn't be so quick to dismiss it. As for crankwalk...BLOCK THE OIL SQUIRTERS!!! Crankwalk is so overrated...people make it sound like it happens to every 2.0 7-bolt. It seriously should be about the last thing to consider when putting a motor together. As long as the squirters are blocked, the crank bearings get plenty of oil pressure and you'll be fine. BTW...I have a nearly complete 2g longblock with 60k lying around if you are interested.

Jay Jay the Jet Plane