I'll bite. I believe Cast Iron manifolds are best long term. That said I would not use stock ones just because they are stock. Fentons are grate but seldom fit well in a hand built Ch***is package. In other words have your Fentons in place then install the steering in the space left. Being I have hand build so many sets of Headers I don't understand why a person that will hand build a total Hot Rod start to finish my be intimated by Exhaust. I mean it's only 3 ports on each side and U-Bends are cheep by comparison and you end up with a Custom fit and grate look. We all know mail order always means some kind of adjustment to make things fit as needed. Dodge the bullet and build what you need.
Back in the 50's ,being poor I would install a p***enger stock on the driver side & drivers side on the p***enger side. This is what I have on my 34 roadster w/a 47truck 59AB. No steering box problems ,only clutch pedal to work around. Seems to work for me. On my 34 5W I have Reds'. This car has a cougar steering box so clearance is a bit tight, the engine is a 21 stud. I also have a stock 21 stud in the roadster at present while I work on the 59 AB.