Metalmeister;
Regarding the elastic modulus for 3XX austenitic stainless steel, one source is ASME B&PV Code, Section II, Table TM-1.
You can interpolate the value yourself based on
Other than the Code the only source that I use in an ASM publication: High Temperature Property Data: Ferrous Alloys, ed. M. F. Rothman, ISBN: 0-87170-243-6