For such an aeroplane, you would need to be a STI(A), not a SFI(A).
'The privileges of the holder of a STI(A) authorisation are to carry out synthetic flight instruction for issue of a licence, instrument rating and class or type rating for single-pilot aeroplanes.'
I don't know where you're writing from, but if in the UK see LASORS H5.7:
An applicant for a STI(A) authorisation shall:-
a. Hold or have held within the previous 3 years a
pilot licence containing an instructional qualification
appropriate to the courses on which instruction is
intended or a non-JAA licence acceptable to the
Authority.
b. Have conducted in a flight simulator or FNPT II
at least 3 hours of flight instruction related to the
duties of a STI(A) under the supervision and to the
satisfaction of a FIE(A) notified by the Authority for
this purpose, or
i. for a STI(A) wishing to instruct on a BITD only,
have completed on a BITD at least 3 hours of
flight instruction under the supervision and to
the satisfaction of an FIE(A) notified by the
Authority for this purpose.
c. Have completed within a period of 12 months
preceding the application a proficiency check in
accordance with Appendix 3 to JAR-FCL 1.240 in an
FNPT of the class or type of aeroplane appropriate
to the instruction intended. or
i. for an STI(A) wishing to instruct on BITDs only,
have completed within a period of 12 months
preceding the application a proficiency
check covering only those exercises listed in
Appendix 1 to JAR-FCL 1.125.