I've not seen a turbo added to a petrol 152 as there are very very few in the UK let alone Perkins petrol engines. Don't think that by adding a turbo you can drag more power out of a worn engine. For it to be beneficial the engine must be in new or extremely good condition. Fabrication of pipework etc is only part of the job. It is essential that your oil feed and return are correct too.
DavidP, South Wales