I'm definitely not squeamish, so just had to had a look.
I find it difficult to believe that was caused just by burst capacitors, but what do I know?
Go on, make a bid, invest in a sand-blaster etc, etc and you could be in business. THIS - photos 5,6,7 & 8 which was my first ever attempt, shows what can be achieved on a corroded chassis just using elbow-grease.
This is rather horrifying. I've never been a fan of liquid cooling. If you can't cool hardware well enough with passive cooling then the hardware isn't efficient enough. I know a lot of people love the G5, but I have always seen it as an inefficient electricity glutton. If it wasn't such a hot running heavy consuming machine it wouldn't have needed liquid cooling to get 4 measly cores.