Thats the question of the decade man. Once 2010, 2011 hits, there will be many cobras that will have racked up some miles and we will have a ballpark answer. Right now theres not enough data to answer that properly simply because theres not many people who have 150k+ mile cobras.
check compression, if its good, theres no reason to not buy it just due to the mileage. only other thing i could think of is the suspension getting sloppy, but $1000 worth of bushings from AC427cobra and thatll solve that right quick.
ive seen far too many people virtually abuse and rape their weekend driven cobras with 5-10k on the clock, id rather buy this one at 123k on the clock thats driven civil on a daily basis than one of those raped and flogged every time they are taken out cause the owner puts up with a pos civic all week and cant wait to have the power on the weekend. Which one you think is gonna give you more issues? Need help? its the one that someone is gonna pay $10k more for cause when it hits 25k on the clock its gonna fall apart.
And iirc its had two top end rebuilds. He had low compression on one bank, tore both banks apart and replaced with revised heads. I think he was good for a while and then had an overheating issue pop another HG and he had to do a teardown again. Not that bad though, if you can do your own work the parts are pretty cheap.