On Monday, England coach Wayne Bennett will announce his squad for the international in Sydney on May 6, which will include several NRL-based players, and he has pledged to keep Super League disruption to a minimum by selecting no more than three players from any one club.
The Tigers have four players up for England selection in full-back Zak Hardaker, centre Michael Shenton, second rower Mike McMeeken and scrum-half Luke Gale but they also have stand-off Ben Roberts and in-form forwards Junior Moors and Jesse Sene-Lefao eligible for Samoa.
Super League continues during the international weekend, with Castleford playing Huddersfield Giants on May 4 before entering the Ladbrokes Challenge Cup the following weekend.
Powell says he has not yet been told how many players he will lose but believes his decision to run with a bigger squad this year will help alleviate any difficulties.
"We've got four in the squad and they can only take three," he said. "Whether they take three or not, I don't know, hopefully not.
"You want players to be in contention, absolutely, but we've got a tough period coming up. We've got three backs in there so that could present an issue but we'll face it when we come to it.
"We've got some good young players coming through that we blooded last year and they did pretty well so we should be all right.
"It's going to be difficult, particularly if we lose three backs, but we're capable of doing it. I think we showed that last year, so it shouldn't hold any fear for us."
New Zealand will not call on Wigan Warriors scrum-half Thomas Leuluai for the ANZAC Test, which is played on May 6, and Powell is hoping Samoa will also select exclusively from the NRL.
Roberts is Samoa's most-capped player, having appeared in two World Cups, and Moors featured for Matt Parish's men in 2013.
"I haven't heard anything so I'm hoping no news is good news," Powell said.
Castleford play fifth-placed Hull FC on Sunday and take on reigning champions Wigan the following Saturday as clubs begin playing the reverse fixtures in the second half of the regular season.
Stand-off Rangi Chase could return for the game at the KCOM Stadium after missing the Easter Monday defeat at St Helens with a wrist injury, but Powell is considering shuffling his pack following a second defeat of the season.
"Some of the guys didn't do themselves justice so it's squeaky bum time for a couple of blokes but that's the way it is," he said.
"We need to get the best performances out because the next two games are key for us."