You will need a charge cooling solution. That standard T16 FPT intercooler will be just about sufficent for this level, use the later mandrel bent boost pipes rather than the cast items as they flow a touch better.
Retrofitting the APC from an FPT car would be the best way to go about it as you will have the benefit of knock protection. However if you do not want to go to the effort or sourcing, removing and refitting it the best solution would be to fit the T16 intercooler, source some type of MBC and book some time on the rolling road. On 97ron+ fuel you should be able to tune to around 12psi safely, maybe a touch more which should give you somewhere around 180bhp (rough estimate), fitting water injection will allow you to raise boost further to around 16psi which should yield your required 200bhp as well as provide a safety net against detonation.
You'll probably have to raise the base fuel pressure slighly (squeezing the existing FPR in a vice to suit will do). A drop in element (ITG, K&N, JR) would also be handy to provide a bit of extra airflow capacity. Standard exhaust should be okay but removing the cat the replacing with a straight pipe would provide less back pressure and a decrease in lag. Timing should be just about okay as the LPT vac cap pulls retard in slower under boost, a bit of a fiddle to pull a little more retard in would be advantagous but the RR operator will be able to advise on this when the cars on the rollers and you have the curves to study.
Total cost would be
Second Hand intercooler, mounts and pipes - £100
Water Injection System (Aquamist 1S) - £350
MBC - £30 for the cheapest up to £300 for an electronic version.
Drop In Element - £30
De-Cat - £30
Rolling Road time - £35 per hour plus operators cost. I'd say 2 hours would be more than sufficent.
Total cost around £130.
Total = £670 using the cheaper MBC. This should provide you with a stable and more importantly reliable 200bhp and probably around 220ft/lb of torque.
Hope This Helps.
Matt
All the above figures and prices are guestimates but should be reasonably accurate