Do you have the appropriate equipment to do a proper valve job? like the tools to make sure the seats are correct and that the guides are correct? When a valve gets hit hard enough to bend it, odds are the guide is going to be a bit hurt as well. You cannot just take valves out and put them back in. Valve buckets are another big thing. You cannot just put the old buckets in. You have to measure them and get the appropriate sized bucket to set the valve lash. The buckets are nissan only and go for ~$10 each (depending on the bucket ect). As for the valves; Nissan is your only option I am afraid.