I feel when it comes to road racing the engine doesn’t matter. Iv ran almost identical times with three different brand kz engines and have seen stockers and mods run the same times. For sprint racing kz is faster over the stockers and mods. I was half a second faster in a kz. That’s just my two cents.
Pevely missouri has a track I cant remember the name unfortunately. ACR here in wisconsin has a 2012 shifter chassis thats only got a hand full of races on ebay. And he can hook you up with some slightly used spare parts.