Director of rugby Chris Willett, who captains the side, has the luxury of a full-strength 22-man squad for the EDF Junior Vase showdown with Doncaster Phoenix at the home of English RU.
And with a Yorkshire Three double over Phoenix already under their belts this season, Cas will start strong favourites to bring the prestigious trophy back to Willowbridge Lane.
Former Cleckheaton back-row Willett insists Doncaster are no easy-beats but remains bullish about his side's prospects.
"My personal belief is that it's there for us to lose rather than for them to win," he said. "Their team cannot beat us unless we don't play and I'm confident that there's no way we've done all we've done this season - giving our all in 30 games - to miss out at Twickenham.
"Doncaster are a good team, they're twinned with Doncaster Knights, of National One, so they're well-drilled and have a very effective pack. And I've got a lot of respect for them for winning all their games to get to the final, even though they've not had anything like the tough run we had.
"At the end of the day it's cup football and they've got as much to win as we have. And they'll be going in as under-dogs, which can always help a team.
"But we're not complacent. We know we've got to work harder than we've worked in order to achieve what we set out to achieve at the start of the season. We're also strong in all departments and have a well-drilled pack ourselves. We have also played together all season and I'm confident our rugby will take care of itself.
Veteran No.8 Willett, whose father Ron played for Castleford RL, has been a driving force behind a second successive Northern Division promotion. An attempt to add the Yorkshire Silver Trophy to this season's successes ended with defeat at Rotherham Phoenix in Saturday's semi-final when Cas rested all their front-line players.
Willett has no regrets: "I pretty much rested everyone. We've had a fantastic season and the last thing I wanted was anyone to drop out through injury. I was determined that the lads who have got us to Twickenham and earned us promotion should all be there to enjoy the moment.
"This is potentially a once-in-a-lifetime opportunity and the idea of someone breaking a finger or tweaking a hamstring, even in a semi-final, was not an option. With Twickenham coming up, the Yorkshire Silver Trophy was at the bottom of our list of priorities.
"Saturday is as big as it gets - I'm still getting texts from lads asking 'are we really playing at Twickenham?'