From what ive seen there are a lot of people there race and rally British classic cars so there must be some places which have the rolling road set ups and are familiar with Cosworth YB engines.
I presume at the moment your engine is, as you think, completely standard and as such there is not much you can do to improve its response, Less restrictive air filter and exhaust will help but as I said the skys the limit to performance upgrades.
The trouble is its addictive, once you start the more you want but of course the money you are going to spend can very quickly get out of control. Tough choice for you which way to go, keep it as standard as possible or start upgrading?