Find out when it last had an oil change. Get it running and warm and pull an oil sample.
Send said sample into the lab and see what they have to tell you. Over all old Perkins are a super reliable engine and pretty forgiving of being treated poorly. There used to be millions of them in farm tractors that just ran and ran.
I`ve had both, similar robust usually long lived large capacity low output agricultural engines.
But, does the Perkins have a manicooler, that may not be so good. Then again I just read somewhere here you can`t get a new Lehman exhaust manifold.
The base engine will last a very long time. The maintenance and or abuse suffered by the hang ons are what determine its ultimate life. Assuming a new to you engine, you can help yourself a lot right now by getting the two HXers professionally serviced and install a brand new water pump. Change all fluids and filters. Ditto the genset.
Pour through the service manual for other needs, Perkins manuals are pretty complete. Take no shortcuts if a new to you engine. Last but not least, engage a good mechanic to assist you in a complete engine go over.