7 1/4 Gear questions (crate 360)

I have 67 cuda with a crate 360, I've been pretty hard on it over the last 3 years and its got a 7 1/4 in it, I'd like a little more take off and I found a place online that sells other gears for a 7 1/4 jeep new, but I was wondering if I put lower gears in it do I risk blowing out the rear end more. Like I said I have had this car for around 3 years with no problem out of the rear end, I've even took it to the drag strip a few times and get like 89 miles an hour out of it. Just wanting to know if its rear end suicide to put lower gears, I have an 8 1/4 but its a large bolt pattern and then id have mis matched wheels. any help would be great.