In early 2018, before I had children and with much, MUCH more free time, I bought a used X61, plus a used X60 1400x1050 LCD, a new backlight, new internal stereo speakers, a new mainboard with an Intel Core i7-5600U from 51NB, plus new SSD, 32 GB RAM, and the original IBM logo of a X60 which was replaced by a Lenovo logo on my chassis. It's the exact same setup as mentioned here [0], except that I built it myself from the individual parts for cost reasons.
The board arrived from Shenzhen after a month or so. I then had to manually fit (including drilling away some parts) the X60 LCD into the X61 chassis, which was extremely stressful. But in the end it all worked out perfectly. This X62 has been my private machine for 8 years now, and I always travel with it. The display still works perfectly, the 32 GB RAM are still more than enough, and it is still very easy to get X61 replacement batteries on Amazon. But the best thing is the form factor; this thing is just so neat and small and practical. Also the quality of the chassis is incredible. Apart from many, many scratches on the lid, it is still in flawless condition.