If you are careful when slipping it out from under the power piston and hanger arms they will last quite a while. That's usually where they tear.
I haven't replaced the top gasket on my carb in at least 15 years but have only had the top off a couple of times. I was running it straight off the jets for over a decade since I was drag racing the car more than street driving it.
Decided to put the metering rods and PP back in it, and add an electric choke and choke flap, that was back around 2004. About 2 years later I decided to zinc plate all the parts and color the castings and just re-used the gaskets as they were in perfect shape.
Kind of a cool story because I also installed full length 2.5 mandrel bent tailpipes at the same time, setting the car up for street use.
We removed the Edelbrock RPM intake and put my "modified" stock intake back in place, and the stock Shaker assembly (had been running a modified one with the 1" taller intake with a custom filter in the opening.
Figuring all this would slow the car down quite a bit but I didn't care because my days of racing nearly every weekend were over.
To my surprise the first outing at our local track the car went quicker in ET after the changes. Not by much as it was already running pretty quick. Our local track is 1/8th mile and the car typically runs in the 7.20-7.35 range for most runs around 95-97mph.
The first run with the "stock" parts back in place it went 7.18 @ just under 97 MPH! I looked at the time-slip and the car picked up in the 60' times with the stock parts which accounted for the quicker ET at about the same MPH it ran with the larger aftermarket intake.
Considering the engine is 455 CID/11 to 1 compression and makes over 550hp imagine what installing an RPM intake does to a much smaller engine making considerably less power........some food for thought........Cliff