Yes you are correct that any change made at the spring will increase 2x at the wheel. You are on track with changing the alignment angles but you need to look at castor. What are you running now for castor? the stock measurement was (+/- 1/2 degree). This was the thinking back 50 years ago but since then its has been found that this ratio leads to excessive bump-steer. Modern first gen upper control arms are readjusted to allow you to get castor to +5 or even higher numbers. The castor addition they give aggressively reduces bump-steer and makes the cars handling feel much more like a modern car. Adding castor changes the forward position of the wheel in the well housing and this alone will improve your rubbing issues. The fix... so to increase castor you have a few options... 1. Put a massive shim stack on the rear side of the stock cross shaft of the upper control arm. This is the cheapest way but you are essentially adding a leverage point that can lead to failure in aggressive driving. 2. purchase offset cross shafts from global west (100.00) this will increase positive camber and castor placing your wheel at at negative 0.5 camber or thereabouts. Additionally it will move the wheel forward in the housing giving you a positive castor number about 3.0 degrees without any shims. I choose this option as seen below because option 3 is expensive. 3. replace the upper control arms with tubular type arms. These arms are re-engineered to give you the correct modern measurements but this come at a price (500-700 beans). If you go this route it is the best way but is not cost prohibitive. Please do not buy the 200.00 hop sing POS off eBay. Its too much of a key suspension part to trust in the hands of the lowest overseas bidder. Finally its all about your alignment guy... You need to have a direct conversation that you want to see the specs before and after. Most tech today will give you a "toe and go" essentially making sure the car goes straight. This is not what you need they need to adjust shims so that it reacts the way you want/need it to. If the tech seems like he/she is in the dark walk away and find another shop! Alignment machines are programmed to give you stock (manufacturers) specs the same ones from 1967-1969 if the tech does not adjust the figures you will get poor results and rubbing! I know this sounds like a lot from a guy on the internet but do some research... call global west and they will give you much of the same information. I have done a lot of alignments in my day and have seen enough go wrong to know where the sweet spot is on a modified suspension.

Looking at your photo... I see the 455 call out on the hood, did you increase spring rate for the larger engine? You may be facing a 2 headed issue. The incorrect spring rate will tweak your specs and may be adding to your issue as well?

If you have not gotten the spacers yet I have mine that I'm not using and ill sell them for a few bucks if your interested.

Here is a pic of my subframe with the offset shafts installed... you can see that it is has a raised "bump" at the mounting points this the size of the change you will need to improve your issues.

here is another pic thats a bit closer.