Forster will remain uncapped after facing the BaaBaas, but Ruddock believes the Newport Dragons backrower, who gets a belated call-up at the age of 33, could make his mark at international level.
"I obviously know Jason very well from the regional level and he has a lot to offer, it is up to him now to seize his chance and become an important part of this squad," said Ruddock.
The new Wales coach has made nine changes, one positional, from the side departing coach Steve Hansen put out against Italy in the final match of the 2004 RBS Six Nations.
Both centres from that match, Mark Taylor and Iestyn Harris, have missed out on the current squad through injury and are replaced by Sonny Parker and Gavin Henson. Two more enforced changes come at half-back with Stephen Jones and Gareth Cooper replaced by a new partnership of Ceri Sweeney and Dwayne Peel.
In the front row Mefin Davies comes in for Robin McBryde at hooker and Adam Jones returns from injury to replace Gethin Jenkins at prop.
Brent Cockbain also makes a return from injury to replace Michael Owen in the second row, with Owen moving to No 8 in place of Dafydd Jones. Jones moves to the bench and the uncapped Forster joins the back row.
"There are a few enforced changes due to injury, but the look of the squad and the side hasn't really changed," said Ruddock.
"I haven't come into this job to rip it all up and start again, we have a strong group of players here which I want to keep together.
"The injuries now mean that some of the players who have been on the fringes of the squad will be given their chance to shine and to prove what they can do.
"We are looking for big performances from each individual and as a unit against the Barbarians as we prepare for a tough tour in Argentina and South Africa."
Wales: G Thomas (Toulouse), R Williams (Blues), S Parker (Warriors), G Henson (Ospreys), S Williams (Ospreys), C Sweeney (Warriors), D Peel (Scarlets), D Jones (Ospreys), M Davies (Warriors), A Jones (Ospreys), B Cockbain (Warriors), G Llewellyn (Ospreys), C Charvis (Tarbes, capt), J Forster (Dragons), M Owen (Dragons).
Replacements: Bennett (Ospreys) / S Jones (Dragons), G Jenkins (Warriors), D Morris (Leicester), D Jones (Scarlets), M Phillips (Scarlets), N Robinson (Blues), H Luscombe (Dragons).
Travelling replacements: I Thomas (Scarlets), B Davies (Scarlets).