Sprockets And Ratios And Stuff

I have a '72 Daytona 500 and she seems under geared to me. I'm in 4th from about 45mph upwards. I know the engines are 'buzzy at best of times but I keep thinking about changing the sprockets to make her rev less at higher speeds (sacrificing a bit of acceleration of course.) All I seem to read around the Web is changing the gearbox sprocket from the standard 19 (which the previous owner said it has, although I haven't checked myself), for a bigger one - probably just up to a 20. But why not go the easier route of lowering the teeth on the (bolt on) rear sprocket? The odd mention of 46 down to 43 has been made, but mainly its talk about changing the gearbox sprocket. I wondered what the prevailing wisdom was on changing front OR rear. What might be best to achieve a more relaxed ride at higher speeds? Obviously the principle is the same for any of you owners, but IF anyone has experience of the 500's it would be doubly useful.