67 Dart Overheats!

Im working on a 67 dart GT for a family friend. It has a stock 340, never been gone though since installed, It also has a 22in radiator that was cleaned before being installed, running a stock 4blade fan.

Car does fine if your cruising but if you have to putt around or idle for a while it starts to get hot. I started off by pressure testing the system, found nothing, Replaced radiator cap, all the hoses, a new 180 thermostate and heater core(started leaking randomly) Last night I even put a I think 7 blade fan on it, without any luck. It DOESNT have a fan shroud, should this fix the problem, or should I upgrade it to a bigger radiator from year one, we are going for stock look so no aluminum. The problem is if we get a shroud and it doesnt fix it, it will not fit the bigger radiator from year one, so then its just laying around. Im going to add some purple ice additive tonight and see how that goes.

Thoughts???

Thanks,
Jack