Just an update, The advice I received above put it in perspective so I stopped thinking about shrinking the port outlet. I had 1-3/8" tube 16g on a 3" radius to work with and even that was hard to find as most 1-3/8 u bends are 2.5" radius or smaller. The packaging is tough even with that. This project has been sitting in my garage for way too long (decades), and a lot of it is I repeatedly over complicate the next step in project, when I should just get it done and put it back on the track even if its not perfect. So a simple 4-1 is where I need to start. Its my first complete header build so I printed out some rough plastic parts on a cheap ender 3 printer to help visualize where I am going. For the collector I also printed out a plastic jig to hold the tube at mostly the right angle to make the cuts. I am still not sure what direction the tubes will run, but realized I need to have a collector to point things at even in plastic, so stopped playing with header legos and started cutting... then I ran out of argon so progress is stopped for the weekend. I am using pipemax from the 2016 group buy here, but some things have to be changed as its not as simple as it looks on the computer screen. If I run the pipes down to the passenger side the primary tubes end up shorter, close to the 19" and 4th harmonic listed in pipemax but the pipe lengths look to be kept closer to equal. If I run them into the fender area the lengths vary a lot more and the tubes could end up really long if I size the shortest tube correctly.
For the collector if I read it right, Pipemax recommends a choke of 1-1/4 to 1-1/2, but premade cones start at 1-1/2? So the smaller options are not available unless I learn how to make my own cone some way. Right now the collector outlet is 1-3/8" but its not to hard to redo what I have done so far. The engines are not that powerful, around 140hp or 35hp per cylinder is about max even when modified, so I am thinking 1-3/8" choke point in the 4-1 collector may be as large as I want to try. I just figured I would post up the plan and see if any more experienced people had feedback or suggestions.