First-half goals from Craig Mackail-Smith and Tom Williams at London Road on Tuesday night earned Posh a place in the fourth round and Ferguson was delighted with his side's performance, despite the young profile of Chris Hughton's team.
"It did not devalue the performance of my team," said Ferguson.
"I thought we were outstanding. It is not my concern who Newcastle play.
"We were well worthy winners. It was just a shame it wasn't more than two.
"Burnley and Derby got to the semis from this division last year. You may need a bit of luck in the draw but I think you can go far.
"We've not really done well in the cups since I've been here because the league has been very important to us, but I think it is about time we had a good run.
"Our passing and movement was good and that was the key. The tempo we played at was good. We knew their team was a youngish one, so we had to be in their faces and play at a high tempo.
"We played at a tempo they could not live with and it was very pleasing. If we had got a third it could have been anything.
"We should have scored more but their goalkeeper was outstanding."
Newcastle's caretaker boss Hughton admitted that it was his decision to field a team of youngsters.
Only three players were over 23 and only two recognised first-team players began the match.
Hughton emphasised that the task of getting the Magpies back into the Barclays Premier League remained the main priority.
"I made the decision before the game because we've got players with a few little niggles and lads that have been involved in most of the games so far," explained Hughton.
"I either played them with a risk of them getting injured or field a side of youngsters. In the end it was too much for them.
"We knew it would be tough with the side we put out. The performance in the first half was not good enough. We allowed them too much possession and gifted them two goals.
"We know we rode our luck but certainly I wanted a better performance.
"I never spoke to the owner (Mike Ashley) about the team selection. I have to protect the vulnerable ones in our squad.
"There is no doubt promotion is the biggest target this season. But I don't want to look upon the cup competitions as something we would be glad to be out of.
"We would prefer to be in the hat for the next round. If we had won the game tonight it would have given us a big lift ahead of Saturday's game."