I swap my front and rear tyres over every two months or thereabouts - so they wear more or less at the same rate. Id rather replace all four at the same time. Whats it going to be? £150-300 for a Mk1 liek a Williams/16V. I can live with that.
I can see that if your front tyres were totally worn and the rear ones not, then swapping over would have an obvious impact on the handling. But at the same time remember that the front tyres being really worn in the first place is worse as they do most of the accelerating, steering and braking: hence the reason they wear quicker in the first place!!!