I've only just discovered this group, and wasn't sure of etiquette - like about swamping it with questions. Anyway, I've no information on sources, it just passed on down the line, or the oral tradition, if you prefer. Anyway, it's a pretty song, pity I can't sing it to you. Here's the lyric:

They say there's a land they call heaven,
Where the children of God they live again,
They crowd around the gates of that city,
And I hope that my Lord will let me in

Chorus.
'Cos I want to be one of his chosen,
When the shepherd's flocks are gathered in,
When the trumpets sound and the pearly gates swing open,
I hope that my Lord will let me in.

They say there the throne shines like silver,
And the streets are paved with gold from end to end,
I dont wanna miss the life thats mine for ever,
I hope that my Lord will let me in.