butchering? they make bolt in kits, and any rx7 person will tell you if you have a motor with over 150xxx miles its not a question of if its gonna blow up but when. a "lil work" wont get you anywhere near the Hp/Tq of a small block in the same chassis. speaking from experience good luck finding a decent shop to do any power-adding work to the 13b, good luck with your build though.