Nigel Brady, a week after winning his 100th senior cap with the province, will captain the side from hooker and is joined in the front row by Ballynahinch props Jerry Cronin and Paddy McAllister.
McAllister has been invited to join the Ireland training squad ahead of their RBS 6 Nations campaign despite missing the last couple of games with Ulster through injury.
Tim Barker and Neil McComb, who have been central to the Ravens' run through to the quarter-final stage, will once again combine in the second row. Conor Joyce, Ali Birch and Mike McComish form a mobile back row.
Blane McIlroy gets an opportunity at scrum half ahead of Ian Porter, where he is joined at half-back by Paddy Jackson who has returned from an ankle injury.
Luke Marshall is also making his way back from an ankle injury and will line out at centre alongside Chris Farrell. Michael Allen joins Dungannon players Chris Cochrane and Conor Gaston in an energetic back-three.
Phoenix Academy forwards Niall Annett, Conor Carey, James Simpson and Iain Henderson are joined on the bench by Belfast Harlequins prop Richard Lutton. Porter and James McKinney provide cover for the backs.
Longwell's charges have not played a competitive fixture for over a month but he believes the current good form of the senior team will inspire his squad.
"There has been a great buzz in training on the back of some great performances from the seniors in recent weeks," he said.
"The win over Leicester in particular, has given the whole of Ulster Rugby a lift. Hopefully we will get a big crowd out at Ravenhill to cheer on the boys.
"It would be a great start to the weekend if we could get a result on Friday night, but we are well aware how difficult it will be."
The former Ulster and Ireland lock added: "Munster have a great Academy structure and have an abundance of talent coming through the ranks. As with all Munster teams, we are expecting a very tough game.
"They will be strong up front and we will need to match them physically if we want to progress further in this competition. But it's a challenge that the players and coaching staff are all relishing.
"A match like this, in the knockout stages against a team like Munster, will do a great deal for the development of some of our young players.
"It will also give some of the senior players the chance to put their hand up. We will be looking for them to use their experience by helping the younger players."
Tickets for the laste-gith game are on sale from the Ravenhill Ticket Office, over the telephone on 02890493222, or online at www.ulsterrugby.com.
The Grandstand and Promenade side of the ground will be open for the game and tickets are priced at £10 (adults) and £5 (children) for anywhere in the ground. Entry is free to 2011/12 Season Ticket holders who can show their pass on match night to gain entry.
ULSTER RAVENS (v Munster 'A'): Conor Gaston; Michael Allen, Chris Farrell, Luke Marshall, Chris Cochrane; Paddy Jackson, Blane McIlroy; Paddy McAllister, Nigel Brady (capt), Jerry Cronin, Tim Barker, Neil McComb, Conor Joyce, Ali Birch, Mike McComish.
Replacements: Niall Annett, Conor Carey, Richard Lutton, James Simpson, Iain Henderson, Ian Porter, James McKinney.