If compare 4A/KE or 13B/KE, but have advantage and disadvantage.
Yes, 4A parts is expensive, but the mantainance of 13B also not cheap. The life span of 4A is much more then 13B. If compare both engine kosong, 4A still cheaper then 13B. If fully rebuild, 13B is much more expensive. But the power given by 13B is almost double then 4A, so consider equal. Depend which you like.
I have try 4A/KE and 4A/86. Both same engine, but in different chasis, is totally different. No matter how much money you pump into KE, KE still a KE. Won't able to beat 86. This is base on my experience, might not true for you.
I haven try 13B/KE, or 13B/86. So can't make any complain. But if its good combination, sure a lot of people include japanese and europe people using already.