I have a 280ZX setup that was on my car for over a year and worked fine with stock fronts but you will need to remove the proportioning valve and retention valve in the the MC. I recently upgraded to the SM Wilwood kit because even with $200 hawk pads they were getting cooked at the track. If your car never leaves the highway this won't matter.
Please don't take what TTT told you at face value. I swapped an SBC in my garage and the rear disk swap was 10x more frustrating to finally get everything working. Also make sure you're aware of what is required to remove the backing plates.
You need an adjustable prop valve. TTTs statement doesn't even make sense, if you don't need a prop valve then upgrading the fronts later would be pointless and throw off bias... Just saying
There is a reason to swap to disks, just do it right or you will end up wasting time and money.