CENs .21 engine mounts - part number CT040 should allow a .21 to fit the ct4. I used them on my funfactor, but found them a little low for my .28. I ended up modifying some ofna adjustable mounts to suit my chassis, not sure if there is enough room on a ct4 for the ofna mounts to be an option tho.

These mounts are the ones that New Era use on their .21 conversion for the Funfactor, I think both the ct4 and the funfactor use the same mounts for small block motors dont they?

Anyway - hope that helps - u have set urself a serious challenge there mate.