Yes, maintenance history is everything with older BMW'S. At that price, you are ahead for when you need to do repair/ maintenance.
I do 90% of the maintenance on two inline six bimmers - a e90 with 62k miles (n51 engine) and E53 x5 with 125k miles (m54).
Ebay is a great source for...
The shrink/swell of cedar with weather changes is going to be problematic with any adhesive. A scrap of hardiplank might be better.
That being said, 3m 4200 or West System Gflex could be considered.
Doing a ATF drain & fill in the "new to me" BMW 2002 X5 E53 (3.0) with 125k miles. The "lifetime fluid " is original from 24 years ago, however it shifts fine.
What fluid do you recommend instead of outdated DEX 3?