Perkins made two turbo versions ... T6-354 and an HT6-354 The H meaning "horizontal" like an old Chrysler slant six.
Both of these engines were made in 3-ring and the more rare 5-ring versions. The 5 ring version they are pure gold as they were originally built as continuous run generators and will give 20k hours easily. both were also used in industrial and farm equipment (tractors etc.) The 3-ring version should be good for about 12k hours.
The only way to find out if it is a 3 or 5 ring is to get the serial number (on the block at the injection pump) and call Perkins in England .... or you could remove a piston and look
It is most likely 145hp but could be 165hp. I forget the website but free service manuals and parts manuals are available on line.
Parts are readily available through most farm equipment places or through Trans Atlantic Diesel
The photo below is my 1971 HT-354