Trek actually made a very wide range of forks over the period 1977 (or so) through the mid/late '80s that look like that, with different rakes, lengths, steer tube lengths, and tubing types. It wasn't just one model, and there were hundreds of thousands of them. There weren't a lot of Columbus ones. There are a lot of current builders who could get replacement Columbus blades and install them in your existing fork crown, and it would end up at least as good and sound as Trek's original.

What does "increased headtube angle mean?" If it's not the same as it was when the bike was built, you have damage that might be very dangerous and absolutely needs to be assessed by an expert.

Why are you trying to add a few mm? Is the steer tube on the new fork a little too long? To accommodate a few millimeters you can add an extra spacer or two between the upper fixed cup and the locknut. This would not disturb the build up of the lower bearing set. That lower bearing set is one of the most highly stressed items on a bike, and needs all the help it can get.

What is the serial number of your frame? I'd like to look it up on Vintage Trek and find the frame specs, and see what trail it was designed for. If it was designed for say 55-60 millimeters with the original wheel, then I really think you'd be best served by getting a fork with the rake Trek designed in and preferably a similar crown to axle length. Making the steering slower (higher value of trail) might really not be a good idea. Another alternative if your new fork is steel is to have a qualified person re-rake your new fork to have the same rake as the old one. This will likely lower the front end a bit, but will get you much closer to what Trek designed it for.

I had a Trek 531 fork re-raked in the opposite direction, no problems no worries. I can even send you to my guy.