Should I buy a 90 740 GLE that has 2 high pitched noises?

[Tom SE Ohio]

A well-respected local import car mechanic fixes up and sells Subarus and, to a lesser extent, Volvos.
He has "rebuilt the top end" of this 16V Sedan - a valve job, new timing belt, etc. as well as new headliner and the car with 126K miles. Also, he has driven the car from Ohio to North Carolina and back with no problems.
We are okay with the idea of the timing belt whining while it adjusts itself (sounds like a jet airplane), but there is another accompanying higher-pitched noise, that sounds very much like the buzzer on an alarm clock, that builds and grows louder as speed increases.
Unfortunately, the mechanic can't figure out what is making this noise.
We have always wanted a Volvo, we like this one alot!
But we could use some advice before taking the final step.
Your consideration is appreciated.

[Volvord]

Timing belts DO NOT make a whinning noise. I would recommend that you not buy the car without these noises being repaired first. The 16V Volvo engine is an interference engine which means that if the timing belt breaks the valve will contact the pistons resulting in expensive engine damage