Op rods are not "really" straight, Chis45. If you examine a new one closely, you'll find a very definitive and purposely installed bend in the rod. Don't try to take it out. It is supposed to be there. I think what the other poster meant was to make sure it wasn't bent more than it is supposed to be which would preclude it from working correctly. They can be bent if trying to remove them incorrectly.
As for your gunsmith hand-assembling an M1 on a CAI receiver, I'm pretty sure it will be done correctly and will be a good shooter. Like anything else, there are exceptions to the rule. The problem with CAI based Garands is that most of them are truly junk having been basically slapped together. I closely examined one about two week ago and was flabergasted as to just how poorly made it was and the way it worked. Everything was loose, poorly fitted, and just plain ugly. If you were to build an M1 using all GI parts on a CAI receiver, properly fit and finished, you'll probably end up with a good shooting rifle. It still won't be able to hold it's value when compare to an "authentic" SA receivered rifle, but I'll be there are a good number of poorly maintained, very rough "authentic" M1s out there too. So, good luck with your shooter. Let us know how you like it. Try to find someone at your range who has one with the SA receiver and compare them side by side with yours. Give us an update and critique.
Rome