-When is the last time your AC was serviced? Are the filters or condenser coil blocked with dirt and dust and killing it’s performance? Is the condenser installed under a deck or somewhere stupid with no airflow?
-Fix air leaks. These are the biggest loss of energy. You can diy or have someone preform a home energy audit where they hookup a fan to see how much air loss there is. Then seal gaps, replace worn weatherstripping, etc and retest. There are incentive programs here in many states to help pay for these audits
-Is you attic properly vented? Look for soffit vents and ridge vents. You may only have gable vents in an older home which is not going to cut it. Your attic becomes an oven if it’s improperly vented. There is a certain ratio of ventilation to square footage of attic that needs to be met, 150:1 if I recall.
-Insulate attic: You didn’t specify your region but 8 inches of old fiberglass isn’t going to cut it in the majority of regions. That could be as little as R20. Adding additional insulation to the attic is cost effective and there are incentives programs to do so. Check what the recommended r value is for your zone. R49 will cover most of the US if I recall.
-insulate walls: You don’t need to tear down the drywall to insulate. They drill holes into each joist bay and blow loose fill insulation in. Then patch all the holes. Same as attic but slightly more work.
-windows: are your windows/storm windows using double pane glass? If they are, how old are they? have their seal been broken? Also look into curtain treatments for windows that get heavy sun.
The very last thing you should do is be looking at replacing HVAC gear. If you do it out of order then you’ll buy oversized equipment that will short cycle when you add insulation.
Also more generally, trees. Plant them. Let them get big and grow around your house for shade. Not exactly an overnight fix but mature trees can reduce massive thermal loads. Especially if they shade your AC from direct sunlight.
And one last note, please don’t add vinyl ontop of your brick veneer. That’s a great way to devalue your home. Yes technically you can put vinyl up with a layer of foam insulation board underneath but that’s really a last resort.