Drivers side header problem (power steering)

I have a 69 Swinger 340 that I have just installed the engine along with a new set of Hedman headers. I have a clearance problem with one of the rear tubes right up against the power steering box and also the steering shaft coupler is rubbing against one tube at the top. Phoned the manufacturer and they tell me should fit ok with about a quarter of an inch clearance.
Also have 2 new motor mounts installed (aftermarket) to make sure engine is properly positioned.
Anyone else had this problem?? Any ideas before I start banging in the tubes? (really don't want to!)