unfortunately neither of the ez-starts will.

I dono why he made that comment, because regardless small block or big block, there are many roto-start kits that can fit both! Heck, redcat even has that written in the description

As per description for item #R-70111T: Starter Gun & BackPlate for VX16 & VX18 Vertex Engines &SH18 SH21 engines (Battery and Charger NOT included) Includes 11011h12backing plate.

Now, I know you have a SH .28, I just used that one to prove a point because it fits small blocks AND big blocks.