I have a bluetop 4AGE in my Locost 7.
If I were to do it over, I would have just bought a JDM blacktop or silvertop and NOT rebuilt mine. It would have been cheaper, and have more power.
However, since I am doing this all again, Locost 7 #2 has a Duratec in the shed. Bigger, better, cheaper, easier to replace, and a "current" and thriving aftermarket.