I've acquired some firkins...

My parents moved house recently, and, when clearing out the garage, stumbled across two 9 gallon / firkin casks from the old Buckley's Brewery, Llanelli (RIP - it was bought out by Brains a while back who then closed the brewery, but still produces one of its beers, the Rev. James). The previous owner of the house must've bought a load of beer for a party and left the casks there. Like the good father of a homebrewer, he has kindly donated them to me.

Though I'd love to use them for cask-conditioned beer at home, I don't know if that'd be a good idea given how quickly it turns once it's tapped (unless I have a party, of course). Otherwise, do you think they would be suitable as secondary/lagering vessels?

Also, they are slightly mucky - it looks like someone maybe used them to prop up boards to do some cementing/rendering at some point. What would be the best way of cleaning them up? Would I need to get some professionals to do it? Could a brewery do it for me? I actually live 10 minutes away from the said Brains brewery...

I've seen where someone used a NEW propane regulator to drop the CO2 pressure, installed after the regular regulator, to just above ambient, with CO2 on the beer it should stay fresh for a long time. Some cask beer aficionados argue that casked beer needs to be open to ambient for 2 or 3 days to obtain a flavor that cannot be achieved any other way, then just put it on CO2 after that.

And to clean them if its concrete you may have to chip it off and then polish the keg to completely remove the stain.