New purchase and some guidance required

[northern_aqs]

Good day/evening,

I recently purchased an 87 944s from a long-time mature owner who was diligent with maintenance. The car has approx 137,000 miles and service records/receipts back to 1992 that total almost $30k. I was able to speak to the mechanic the PO used for the last 16 years and am comfortable with the purchase here North of Toronto for $5500.00 with the only need being tires. I was looking originally for a turbo, but unable to find a car with the mileage, history and condition I was after, I'm pleased with the S instead.

The good:
Lots of maintenance history
No accidents or repaints
16" Cup wheels (not sure if they're the cup or as the PO described "club sport")
Everything (as in everything) works.
S2 air box
After market chip (can't recall the brand off hand but have the documentation in the files)
Short shift kit
930 steering wheel
968 mirrors and door handles
Rear Turbo wing embelishment
Timing belt replaced at 136,000 miles
Factory "sport shock absorbers" as per the COA
Re-sealed rack with new lines.

The bad:
A few not so appetizing modifications including a poorly painted valve cover and cam tower cover.
White faced gauge stickers
Leaky valve cover.
A belt whine from the timing belt area that sounds like I'm running a roots blower.

The belt whine is alarming to me and only the fact that the TB was so recently done comforts me enough to drive it at all while this is being identified. Based on the receipt for the TB and speaking to the former mechanic, the tensioner, belt and balance shaft belt were all changed; is it possible that, as the mechanic suggests, the sound is normal for the belt initially after replacement? I can hear it inside the car while driving with the windows down, at all speeds save for on the highway. Short of throwing parts at it, (re-doing the timing belt) as my regular mechanic has suggested, can anyone provide some guidance? Is it possible the timing chain/guides could be responsible?

Thank you all for your input, I'm excited about the prospect of enjoying a car I've appreciated from afar since I was a kid when they came out.