fast road are good - I have 268/270 (longer duration than this will make the car a pig in town) in my '89 - and past 4k rpm it sings.
They cost roughly 450 quid from everywhere - Piper or Kent.
You will have to port and flow your head and fit a 4 branch manifold to totally enjoy the experience though.
"It's all about getting fuel/air in and exhaust out!"
