I own a 1964 Chevy Belair 283 V8 hardtop. It has 79400 original miles, car is all original. Question is do I replace all four drum braking system to disc or just front? Would this de-value the car? please help, trying to restore but do not want to de-value the car.

If it's museum quality, keep it original, but if it's intended to be a driver or cruiser most buyers would see that as an upgrade and it would boost value. The fact you are restoring it and it has nearly 80K miles indicates it's not one of those ultra rare low mileage museum quality survivors, so by all means make the upgrade. Personally, I hate old brake systems and would never put one of them on a modern 70+ MPH highway. Just too sketchy. If you do run your own brake lines, be sure to use a good flaring tool as well, you can rent a $500 tool that makes professional flares, versus those crap $20 flaring tools. My buddies shop handles some resto mods, and biggest problems with owner made brake jobs are flared lines popping loose (along with the resulting fender bender).

Thanks, I'll go with the upgrades! Would be safer to drive and show. New Question the 283 V8 engine oil? Some people say use the new oil and some say use a Zinc supplement oil? Would it be feasible to keep engine original or upgrade engine as well? Thanks Matt