[kk2002s]

This is good place to bounce ideas around
Boxster S first appeared in 2000 Model Year so this car, 1998 would have started life as a Base

Replacement engine would most likely have same IMSB that any 2000 would have, not the replacement version other mfg make or the larger version found in 987s

$7500 I don't know, depends on condition all the way around and how much and how long ago preventative maintenance items were replaced

And that's the stage this car is at, 18 years old 120k miles.
If your willing to learn how to replace things then the cost is somewhat manageable. Otherwise having to pay someone could be a bit expensive.

I'm at 14 years and 87k miles and just went through a whole list of replacement maintenance items. Doing myself helps on the $$$ side but there always seems to be a list

Don't be deterred. Fortunately Porsche made a lot of Boxsters and there are many well cared for ones out there