Rover...what kind of Rover?
The engines are nearly bullit proof.
The turbo's too for the most part.
450 psi sound very good on a used motor but not out of the way...they'd usually be 350 or so....depends how the compression reading was taken....personally I use a leak down test....it does not rely on an altitude adjustment.
The block and head has a very good reputation..the weakest link..if you pardon the pun...is the timing chain, and next is the vacuum pump.
Rover ?
Oh yeah...welcome to the errrr, Rover forum ?
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