Think I'd agree with you Les. A light clean up is the best approach in this case as everything is already pretty much spotless
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When I first got my '75 (some 14 yrs ago now) I had it professionally rustproofed, so all the arches (and more beside) are covered in black industrial strength Waxoyl. I don't regret it, as it has kept everything rust free, and for the first 10+ yrs of ownership the car was driven daily up and down the M25 in all weathers.
Now I keep my '75 for "high days and holidays" as they say, and I keep the wheel arch areas spotlessly clean. The Waxoyl is holding up well, and the undersides look pretty smart, but they will never look "factory fresh" and original as yours do. As you know, once the originality is gone, it's gone for good.
Step away from the paint can and pick up a microfibre is my advice
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Cliff