I'm assuming that it matters which side you put the valve heads back on. If that is correct, how do I know for sure which head goes back on which side?

If you can't tell the difference, chances are the engine won't be able to, either. Seriously, they're the same. There IS no left or right. A neighbor?

RACE ON!!!

no difference what so ever. proof of this if you have any doubt is in the GM catalog. the corvette head has 1 part number. if you have your engine torn apart the only thing you might look for is the coolant sensor. both heads can accept one but one head has a plug and the other a sensor. i overlooked this assembling my engine & have my sensor on the wrong side. i thought about switching the sensor to the other side but the plug was totally frozen & i didn't want to use a easy out on a new engine. that being said i just ran the wire a little longer & it worked just great.

Thanks both of you. You are correct, it makes no difference. Thanks again!

It is easyier to put them back on the side they came off of only if the coolant sensors are differant, or only on the one side. Sometimes those sensor plugs are a real bitch to remove.