synthetic oil or regular

i just bought a 96 200sx ser with 51000 :grinno: miles on it. yeah a very good find but i want to know if changing it to synthetic be alright on the engine. also i read the original manual and it says to put at least 87 octane(regular) in it. could i up the octane also without anything happening to the engine. oh i do plan on puting perfermance parts in the car possibly a turbo down the line.