Looking to put an 83 280ZX engine with a p-90 head in my 240z. The question I have is concerning the hydralic tappets. Will I have as much performance with this engine as with valves that need adjusting?

The P90 head has the solid (adjustable)lifters, not the hydraulic lifters.

No worries.

If you do have the P90a head, yes you will do well with that head, just from experience and from what other high HP Turbo guys at least all run the solid lifter heads.

I plan on switching myself as we all know that oil will compress easier.