Looks like you're SOL - these were rare five years ago - and the ones that were around then were made of aluminum.
Maybe set up an ebay search - which will email you when one appears. Just remember that aluminum blocks can corrode from the inside out - even if they were run in cooling loops that only had aluminum or plastic in 'em.
If you are looking to make your slot 1 box quieter, maybe just look at yard sales for an old Dell box - their slot 1 boxes had a multi-pin-array heatsink on the processor and a "hood" extension from the power supply air intake going over the heatsink. These were not particulatly quiet - but if you replace the PS fan with a panaflo L1A or Nexxos 80mm it is.
I've one of these cases in my garage waiting to go to the recycling center. You can have it if you want to come get it
Includes slot 1 processor (with multi pin heatsink, motherboard, 64M memory, 1G drive, 200W power supply (with hood). Not worth paying for shipping, of course... Oh - I have it because it belonged to a client who wanted his old data taken off it and who didn't want the box back once I'd done that...
If you are looking to make your slot 1 box faster, well, I
think you won't necessarily find that in water cooling...