Beavon hopes to resume his role in North End's attack after departing midway through the first half of last weekend's 0-0 draw with Leyton Orient due to concussion.
Former Tranmere captain Welsh missed the O's visit to Lancashire having suffered an Achilles injury in the 1-0 defeat at Brentford a week earlier.
Fellow midfielder Joel Byrom is building towards full fitness following hernia surgery and has completed another week of training, leaving Scott Laird (broken leg) as the Lilywhites' only remaining long-term absentee.
"Portsmouth have picked up a little bit in recent weeks and they are in quite good form," said Preston defender Paul Huntington on his club's official website.
"Obviously they have had difficulties off the pitch, so it has been a tough season for them, but on the pitch is what matters on Friday and as of late they have been going well, so we will be expecting a tough game but it's one we are looking to win."