Great story Marvin. It's a lot of work, but the dividends are worth the effort.
It's even possible to just "move on" from where you are and ignore the old QSOs.
As some of us get older, we put up better stations. When I finally became a bigger gun, I also found (especially over the last couple of "peak" sunspot years) that I was able to replicate just about everything I had previously done. Not all, to be sure, but plenty enough.
So, if someone reading this just can't bear the thought of typing in all of those old QSOs -- just don't. Pick up from where you are and you'll be surprised at how well you do.
Or, just sift through the old cards (does not take that long) and "pull" all the rare stuff. You know what it is, so it's not the big a bother -- or that big a volume. You can turn in the cards for credit (if you haven't) or simply type in that relatively small number of QSOs.
If you've turned in some DXCC in the past, its nowadays pretty painless to download the whole bunch. That's right, whatever you have credit (even if it 100 old card only submissions over the years) for is not all that hard to import into your logger. There's an option to download ADIF for your whole account. It used to be obscure, but now it isn't. So, you can do "from here forward" or even, with only a bit more work "from here forward plus my existing credits."