I'll answer and Rob can add to it if needed, we thought we lifted a head when we were in Fallon, when we pulled the motor and checked the heads couldn't find anything for certain. We have a real small expansion tank on the cooling system, we may have just gotten it hot and blew coolant all over the place. Wanted to swap motors anyway, this one has a filled blocked and the heads are a little more tricked up. We also bent a couple of push rods in the last motor so want to have the heads looked at and the valve clearences checked.
I decided early on having a spare of about everything is probably a good idea at the hp and et's we are trying to achieve.