Sulfuric acid is a tricky chemical to deal with since its corrosivity varies with concentration, temperature, impurities, and velocity; sometimes in unexpected ways. According to MTI Publication 1: Materials Selector for Hazardous Chemicals: Sulfuric Acid, a high-silicon austenitic stainless steel would work for 98% sulfuric acid at 75 °C. It is possible a Hastelloy B type alloy or high-silicon cast iron would also work. Many plastics can suffer from environmental stress corrosion cracking (ESCC) in the presence of sulfuric acid so plastics choices for 98% acid are somewhat limited, especially at 75 °C. Again according to the MTI publication, ethylene chloro-trifluoroethylene (ECTFE), ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), perfluoroalkoxy (PFA), and polytetrafluoroethylene (PTFE) are all possibilities for 98% sulfuric acid at 75 °C. You may want to get further and more detailed guidance from one of the many references and standards published on this subject.