When using TA roller rockers on our aluminum 350 heads, the exhaust rocker will not sit directly over the exhaust valve, it will be off to the side. This is normal, due to the exhaust valve being moved from the factory location to allow the use of a larger intake valve. This won't pose any issue to performance or reliability, but if you want to correct the exhaust rocker location, install this  retrofit kit. Requires machining (shortening) of the spacer tubes.