Hunting over bait as seen on TV shows in Saskatchewan,the broadside shot should be OK with a smaller gun with a good bullet but how about the buck facing you and ready to takeoff?
Neck shots are less than ideal and center of the chest through brisket may or may not work with a 243/25-06.

270 with a good bullet is where my comfort zone would begin for that angle or else you wait for the ideal shot or pass IMO.