Yeah I'd read up everything you can about the injection pump. As Jason suggested I'd make sure it's fit for starting first too as that's most expensive and critical part. Fuel filter should be changed and I'd suggest priming it with Lucas diesel injector cleaner after cracking all the injector lines to bleed air out. It surprising how much air can be in there.
As far a maintenance you should always be running a fuel additive too to help maintain the pump seals and keep the injectors clean. For oil, 1 gal of 15-40 rotella is $13.99 at farm and fleet, its what I run in the M20's anyways.