My experience is the extra 8 cores are definitely worth it.
64 gb ram should be plenty.
I have an nvidia card with 4 gb ram like you and its very good.
I would recommend a secondary internal SSD drive of 1 tb.
Run your projects on that, and then dump to external drive to make space later.
1500 photos is a lot, I typically do 400 or less for my drone flights.
The 20 laser scans part seems huge to me.
Maybe if doing mechanical stuff they are not too bad, our civil ones are 100 million a scan.
The other thing is its not great to buy high end now, and have it last 5 years.
Its better to go medium high now, and buy new in 3 years. Things change too fast.