Fir 400bhp the CR can remain the same, you want this as high as you can get it, without lowering from the std CR.
Std cams will do 400 no problem, and be very driveable.
A T34/35.48 will do 400 all day long and give you the least lag.
If you have the engine apart I would pocket the pistons as even with std cams pistons the valves can clip, though mine is safe at 7300rpm.
The RS500 cooler is a must, other things that are a good idea are a fuel pump rewire, light de shrouding job on the head, about £275, DON'T enlarge the ports, you need to keep gas speed as high as possible.
A ARP stud/nut kit is a must as is a group a head gasket, but it ABSOLUTELY MUST BE RESTED WHEN FITTING.
I would also go for lighten balance while apart, and if funds allow get rid of the ecu for a more up to date managable one, or at least a L8, with lambda control.
tabetha