I think what others have done if you search the other threads is mill a few mm off the mating surface on the top chamber. A small amount (.5mm) can also be won by using a thin smear of gasket goo between the mating surfaces rather than the gasket, and another mm or so can be won by filing off the top highest edge of the plennum chamber.
You can also ease the bonnet a little (ie bend it) to give a bit more clearance but you have to be very careful how you do it so it doesn't show. I stretched mine using a flat piece of softwood but marked the bonnet in one spot by using a too narrow piece at first. A piece of floor boarding about 6 inches wide worked a treat leaving no marks, but the initial damage was already done unfortunately.
I assume you know about the VVC RH engine mount available form Caterham? It drops the engine a large amount to clear the bonnet but then you do need the dimpled cross brace. If yours is the race chassis so you can't replace the brace, it's possible to win a bit of clearance by shaving a couple of mm off the exisitng RH engine mount, but you would have to be careful not to weaken the weld at that point.
C7 CDW