Good results can be had,but if you do it and its a mess,to rectify it will be a nightmare,may need lots and lots of work to get rid of the paint ready for a proper respray,even just flatting down with a DA sander and spraying a barrier and top coat would not work.Because hand painting tends to put a lot of paint on. It then becomes too thick a coat and causes cracking when the panel contracts and expands.
Ok for a banger to tidy it up,no good for a decent restoration,depends what you want it to look like,and how much you want it to be worth afterwards.
I have seen acceptable hand rollered,but takes about three times as much skill and time as a half decent sprayover.There aren't many decent old coachbuilders left ,we had one in our family garage when I served my time he was truly a craftsman,he could hand paint a panel and it was like a mirror,but I could spray a whole car in the time it took him to do one wing,Thats why there aren't many decent old coachbuilders left ,apart from them all dying out and no one wanting to do it the old way.
You may like the finish you may hate it. But good luck with it.