So are you thinking about
replacing the existing rubber boot with the leather one? I don't know much about the '68 and '69 that only had the rubber boot, but the later cars had both and from my experience with my '76, it's the rubber one that does the bulk of the actual "boot function" - the leather one is largely aesthetic. You might not get the heat and sound insulation you want from just a leather one, but I could be wrong. I guess since your current one is torn up, anything will be better than that!
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1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.