Good luck with it Tom. Unless you end up with rediculous amounts of downthrust I don't think you will have any problems. Certainly not any that will jeopardize the airplane during test flights. I had a Sea Fury which had excessive downthrust and the only time it was a problem was in a go-around situation as it would pull the nose down when full power was applied. Had to be quick on the up elevator if you were very close to the ground to prevent it from skipping the main gear. However, it was probably the best point rolling warbird I've ever flown and I've often wondered if the excessive down thrust wasn't one of the reasons for that!