I would check the whole thing over (especially if new to me), FGA, inlet pressure, air intake readings, check safety devices, seals, operation, you know a safety check. TT is also good, helps me sleep at night. Get the gas safe booklets (B&Q sell them) they are idiot proof and if you fill in all the blanks you will be belts and braces.
Also leaves a paper trail that you checked all these things and it was safe at the time of you checking it over.