Lets discuss my cooling

Ok here is the set up. 71 Scamp, 360, xe268 cam, magnum heads, air gap, Holley 670, TTI Headers, 727, 3:73 gears. Pretty sure that is all.

Now with that being said, the car originally had a 318 and never over heated, didnt matter if it was idling or driving. After I put the 360 in it, I cant get it to cool worth a crap while at idle. Once it starts getting hotter, it never really seems to cool back down but will sit at that temp or rise more if stopped. Until I am forced to pull over and shut the car off to let it cool back down.

Now I do have the stock radiator in it and some of the fins are toasted and disintegrating in a lower corner. Running the factory fan, I also have never had the shroud for this, which I know will help but how much?

So what are your thoughts as to my situation and why I cant get it to cool worth a crap. I would love to get it to the point I can idle in traffic or at a stop sign. Thanks

Does it stay cool on the highway at speed?