Post '67 K frame in an early A?
A member over at slant six.org (he might be a member here as well) sectioned a 73-76 (IIRC) K Frame to early A width. I don't think that it worked out too well
Seen that years ago. Was afraid to mention it, if someone thought it was a good idea.
Bottom line most of the header clearance issues come from the narrow frame rails.
An alterkion would help with steering box to header clearance. It moves the steering linkage up front, so it eliminate steering linkage clearance. BUT It’s not going to change the frame rails. And you’ll have to check if the new steering shaft creates another problem (not likely).
But what are you trying to accomplish?
TTI has an early A header that will fit, correct?
Are you trying to fit a 67-76 header in there. From TTI they are the same price as the 63-66.
A thorley 67-76 header is cheaper. But is all the fab worth 200-300?
If you’ve got some special race header an alterkion may help. But if the header hits the inner fender and/or frame rail, there’s still a problem. And you’d have to know if the Alterkion steering shaft clears too.