which headers are best?
There is only ONE header to use in your application. You MUST have manual steering. They are no longer available new, but I found a used set and have seen others for sale. They are 5303 Hookers. There is nothing else that fits and works like them. Not dougs, not Hedman, not TTI, none of them. The Hookers are a giant PITA to install and they are very tight, but once installed you can get to all the spark plugs, oil filter etc.
In a pinch, you can buy Hooker 5204's but they are small for your application. They work and fit as well. You can buy the 5204's new.
Don't skimp. This ain't a dinner date with a bimbo. It's a serious commitment.