We did that on B737-236, G-BGDS (or was it GDO or GDI) in 1985, after the Manchester incident. Put a -17AR on in place of a -15A, just operated at the -15A settings, the rented engines didn't come with auto throttle LVDT and wiring.
Remeber, but not clearly, the AMM having the info on mixing engine models, and check the fire detector system manufacture.