Guess it comes down to whether you want them ' nice ' or ' correct length & sequence' looks like there is a 'higher degree of difficulty' in having both. One point being missed here is that 'modern camshaft timing & higher RPM limits' mean that the primary pipe length should be shorter which makes the crossover design difficult to engineer into the space available.
Checked all the pictures in " The Ford that beats Ferrari" all of them show exhaust systems with the same set up as Adams. So for the guys looking for originality the "wrong order" on the 1467 collector is the correct thing.
May be we missing one very important fact, which probably is, that it doesn´t matter at all :lipsrsealed: as long you have the correct ones are paired and a nice perfectly made merge collector is used.
My RCR System is following this originality route and the headers are fitting perfect without any tension to the pipes, Which in itself is worth a lot.
You're right. The firing order in the collector is only secondary. The 180 degree connectivity is the most important. I have a buddy that worked in F1, and he claims that they found power with the rotating firing in the collector. It is easier for the flow to reestablish when the tubes are next to each other rather than diagonal but again, it is secondary to length, diameter, and bank to bank connectivity.