I can get my Surpass 1.20 to fit in the supplied mount by flexing out the beams 1/16 inch each side. The engine has to be pushed into the beams and its tight but it fits. The Saito might be wider but give it a try, it might work! If not, Dave Brown Products makes the next up size , the 120FS mount which has almost identical firewall monting holes as the suppied 90 mount in the kit. If you go horizontal, you could use the same holes in the firewall.
I agree the assembly is super easy!