not an suv expert but i do own SJ410 original soft-top as well, swapped with g13bb 16v with jimny's diff and 4x4 gear! believe me its been more than 2 years now and i never faced any problem on coils or anything just kept it properly maintained, g13 is a fun to drive in this little thing, it never let me down. what i think is this totally depends on quality of swap done! 4age is a good choice but tbh you really don't only have to keep an eye on hp figures, have you thought on suspension? how will you make it stable? did you even think on power to weight ratio ? ohh and how can you forget torque? you are considering a 4x4 thing not a drag car you need torque on lower rpms! there are alot many choices available m13 from a jimny is a good option even g13 or g16 aint bad just find a clean motor and swap it properly that would be much easier! if you want more power than simply built them or even if you do port/polish job on head, bigger injectors, bigger tb, ported intake mani, light weight pullies, chipped ecu etc and most important a proper tune that would be really enough? wont it? a month back even i myself planned to swap in some bigger motor searched and discussed with many persons first i was thinking on 4th gen 3s-gte manual but soon i had to drop this idea as we need torque here, 3sge beams blacktop (5th-gen auto) is really a nice choice if you plan to go bigger as this motor provides all the torque at 4k rpms and that's what you need and don't forget 197hps on stock. even 3sfe is not a bad option and regarding differential i did search on them and rav4 diff are available in bilal ganj that is the best choice with 3s!
and yeah if you can contact mean 4x4 machine guys here in Lahore they can guide you best i would say rather they are doing a project on sj410 with 5vz-fe! yes you heard me right 3400cc out of a surf
attaching picture of my sj410
btw you own that liana now? Isn't this the same owned by guy awais in bwp ? i wont say anything on power-train but my 2 cents on car's exterior make it presentable don't rice it please, remove that huge bench from back, take of those fiber bumper get a quality paint job done keeping it decent yet different from rest
and all the best on your project (y)