The ONLY gas engine I'd ever consider for a MOJO 60 is a DLE20.
It is the only one with anywhere near the right HP/weight ratio that I've heard of.
The problem with the DLE20 is the throttle is real touchy near the low-mid range and may
cause problems keeping a hover stable.

I have no experience with that JBA15 but if it's under 24oz with ignition and muffler and
has enough power to spin a 15x6 MAS-S2 at 9500+RPM then it might work.

I still wouldn't do it. Saito 100 is proven to be the perfect combo.