Luke,
Yes you have to grind away part of the block to fit the starter but it is quite straight forward. A 41/2 inch grinder works well.
I have details of the wiring alterations if you need them!
The plenum does need machining but Caterham exchanged mine!
Did you get the VVC fitting kit with your kit? It is necessary and includes spigot bearing, sump etc.
Martyn.