Hi Matt,
You should have a great set up with the engine and the United.
Bob gave me the Lost Foam set up he used on his Sabre which has a lot in common with the original United. Bob told me he built them both at the same time, just got into his Sabre first and went with it. He won every contest he entered in 1969 with the Sabre, including the Walker Trophy. It was probably just as possible that he could have done it with the United.
BIG Bear
RNMM/AMM