I have to reiterate as I just re-read your post. I answered based on my preference and didn't provide and answer to your question.
If the wind is upstream, you need to get the anchor upstream to prevent hooking yourself. This is because a cast from the right side made with the fly on the left crosses over and hooks you along the way. This is also true for the left/right.
Given that the wind is upstream, choose a cast with the anchor / fly placed upstream. The most intuitive is the single spey, which is an upriver anchor cast.
An easier cast for most is the snap-T or snap-C, which puts the fly on this angler's right before sweeping out the d-loop (backcast).
One of those two would be best for an upriver wind.
In this case, putting the anchor to the right would let the hook blow into the body during the cast. Therefore the anchor / fly must stay on the left.
The easiest cast for most people to learn in this case would be the reverse double spey, although I would strongly suggest practicing left-handed from the start. It pays big dividends down the road.
Another than is fantastic for this case is the snake roll, which I would suggest learning with the left hand up as well. However with care it can be done reaching across the front of the body with the right hand up.
Details on these casts will be provided in our cast glossary over the next several weeks. Better yet, read Simon Gawesworth's new book and watch the Rio International Spey Casting video and/or Derek Brown's video for visual reinforcement of the written descriptions.
Of course it will be my pleasure to work these casts with you in person on the Gaspe' rivers