Pull them as close as possible to 180 degrees off the lean. Are they ash? They will break off with very little side lean and you will lose a few degrees from the aim direction to the heavier side. One easy way without using a modified felling cut is to aim a few degrees to the tension side If you have canopy room. I personally wouldn't put much if any pull on the trees but just set your wedges and walk away. Ash are very prone to barber-chairing.. Perhaps not as bad on back-leaning trees if you keep the undercut in the tension wood. (Not too deep with undercut) Don't leave to much holding-wood. A regular under cut is fine. That means it's not less than 45 degrees (1:1) the steeper you go then the easier it will be for you to line up your cuts. Looks like the dead one first then you have move room to fell the other away from the tree it is touching? Keep it simple. Fall them from the tension side so you can MAKE SURE 100% that you don't have a bypass cut at least on that most critical side. Remember it's 3 precise cuts. Don't go to number 3 if number 1 and 2 aren't right. You start with $hit..you end with $hit. Get that first cut level.