If you want to use the factory perches and have the bolt through the back of the motor mount use these.
https://www.summitracing.com/parts/ens-3-1156g
I used factory perches with those motor mounts on dirty dingo sliders. It can be a pain by yourself to get the bolt lined up going from the perch to the motor mount since you can't really see it.
Do some aftermarket perches that have the bolt through style change the motor height/position compared to the factory perches? I see some people run the AC compressor down low and some move it up because of clearance.