Have I got this correct, your basically making a TR5? Your want a 2.5TC engine to mate to a TR4 gearbox so what has the fine spline clutch got to do with the set up?
As said your Vitesse probably had a Vitesse flywheel fitted to suit an uprated 'small chassis' gearbox and clutch. Now you would probably be best off with a 2.5 flywheel as it is designed to work the 'large chassis' gearboxes and clutch like the TR's....