You could call this Vivaldi's Concerto Grosso Op 3 No 8 or you could call it Bach's BWV 593. Its both. Here is Bach's organ transcription of Vivaldi's Concerto in A minor for two violins and strings. Enjoy.
Loively rendering Bill of one of my favourite Bach organ transcriptions - I have worn out Peter Hurford's Decca recording from the late 70's. The bigger organ sound you have opted for sounds eminently fine in this piece, and the tempo is well chosen. Which organ stops did you use - and are you going to do the other 2 movements?