A good compression test will not guarantee you that the engine has no issues. However, a bad compression test will guarantee that you do have engine issues. Considering that this car appears that it has not had the most appreciative owner, I would consider a compression test a must. I would also highly advise a complete PPI (did you contact Bram?). The clicking you heard could be the lost motion assembly in the valve train which is a really common, non fatal problem in early cars and fairly easy to fix with later versions of the LMA. It could also be excess valve clearance or it could be something bad.
The wear and tear on the car is probably higher than the norm for NSXs, particularly if they are owned by an aficionados. However, it is probably better than the average 1991 car on the market. Things like cracked signal lights are an annoyance if you are looking for a perfect car; but, not necessarily a sign of abuse. The evidence of repainting and panel alignment is a bigger potential issue and certainly warrants the $ spent on a PPI.
When I bought my 2000 in 2011, there is no way that I would have paid the asking price for the car that you are looking at. However, that was then and this is now. The market has definitely changed. I would not necessarily write the car off; however, based upon the photos and the lack of records, I still would not pay the asking price. Assuming no significant damage, it would take $5000 - $10,000 to get the physical appearance of the car into something that I would be happy with (somewhere between #3 or better). Engine & Drivetrain issues would be on top of that.
Hagerty US pricing puts a #4 condition 1991 at around $28,000 US, so this car is kind of in the market price range. I would try to negotiate a lower price because you likely have a lot of maintenance issues to deal with. Don't buy it without the all important PPI. Also, if you are not going to be happy with the cosmetic issues, after you add $10,000 on to the negotiated price to fix that stuff, you might be able to do better elsewhere.
