Rifles may be an assembly of "parts", but they're not a 'kit' that can be assembled without serious regard for those parts.
Well, I do thank you for your help on this.
Boy is this news to me, all short action receiver bodies are not the same !
I wonder if I should get the conversion mag/follower and see if it feeds OK,
or seek a trade with someone, action for action.
It sounds like I could single feed it anyway.