One of the best websites I've found for wheel spec comparison is willtheyfit . com
9.5et38 will place the tire basically where it is from the factory, but the wheel itself will sit 4.4mm in from where the factory wheel is.
Since a 12.5mm spacer on the stock wheels will make it flush, you can add the extra 4.4mm inwards that the new 9.5" wheel allows so you can do up to a 16.9mm spacer (call it 17mm).
I think a 15mm spacer will do fine with those new wheels
definitely post up pictures when you get them mounted