Of the 2, it will not matter.
The Stealth is a square bore and the Action Plus is anspreadbore.
The advertising pictures are not correct OR maybe it was an earlier version. But the Stealth I have is a squarebore.
The port alignment wasn't to good. Workable though. I made a post "When stuff don't fit" with pictures of the grinding I had to do on it to bolt it down. The RPM-AG I have is much much better fitting.