Seaking advice on buying "road race" modified SC or 3.2L (w/ an example)

[Anje]

Dear fellow old Porsche enthusiasts,

I would please need your feedback & experienced advice on making an old dream come true: finding a nice & fun old 911 has been a long time dream of mine and now is the time to find the one
I'm looking mainly for a late 70's / 80's car that would have been modified with taste to have some road race / "Hot rod" feel to it. I prefer cars that have been finely modified and tuned for performance over the years by a loving owner rather than all original & "matching" ones. And it often also helps making them a little cheaper which is good for my limited budget in those days of the after that crazy bubble we have seen the last 2-3 years.

That being said, it seems difficult to me to "value" modified cars especially since each one can be unique, but do you have some "rules of thumb" to share on how you value such modified cars?
Do you have any advice for looking at modified / hot rodded cars? Any particular experience, DOs / DON'Ts to share?

Secondly, to be more specific, here's a car I saw that is the kind of feel I'm looking for and looked like a nice cool one:
Hot rodded 3.2L on ebay
What do you think of this particular car? How much do you think would be a fair value?

My initial thoughts on fair value have been where the bidding about ended, but the seller wants significantly more.

Thanks in advance for any advice or input.