Would not touch it with a bragepole at that mileage and price, I bought my ZTT with only 117K on it 2 years ago nearly for £3K and they want half the money for an 04 75 with over double the mileage on it.
Nearly 300K for any car is a lot of miles and I have driven many cars and vans with 200K+, 300K+ and a 400K+ mileages and all have not felt as good as a lower mileage vehicle to drive in general.
Thats just my opinion though.
Simon