I've been consistently happy with Adrian Flux for two kit cars and a host of slightly cranky old British bikes. If you have the right profile they are dirt cheap even for stuff that exceeds 100bhp/ton and they are wonderfully personal and professional. I've used Footman James in the past and been no less happy. Check with your owners club as both have discount arrangements with some clubs. Certainly in the case of Adrian Flux, membership of the club costs less than the discount.