Rover V8 4.6 fit top hats or not

[Ianstaffordshire]

Hello looking for a bit of guidance here, today I stripped down the 4.6 gems engine I brought to rebuild and fit in my tvr wedge eventually I was intending on fitting top hat liners as I read they can slip the old ones however now it's in bits it doesn't have liners fitted so is there any benefit from fitting them I intend to up the compression to 10.5 to 11:1 and fit a fast road cam it already is running canems ignition with slightly larger injectors.
What hp should it realise anything over 250 would be nice.