New to the game, would like to have a rifle built, is there a limit to what barrel contour you can have?

As a rule of thumb You are best off using a sporter contour with a 24"-26" barrel. If you go with a heavy barrel it may not make weight. Good luck and post pics when its done.

Different weight barrels for each class. Are you shooting Hunter, Standard… or both?

if you are shooting this rifle in both classes, hunter & standard, rifle weight is a concern. If building for hunter class rifle a #4 contour will work. Using light weight components you may get away with a # 5 contour, some also use a #6 fluted. Stock weight needs to be kept under 2 lbs and light weight scope with 1 inch tube.
Hope this helps,
Brett

I have a 24 inch 6 contour bbl that was fluted and it makes weight for a standard gun.

The different barrel makers have their own contours, thus they will weigh different. Your best option is to weigh your stock, action, rings and scope, and then you will know how much your barrel can weigh. Next decide what kind of barrel you want and call the maker and speak to a barrel tech not the lady that answers the phone and takes the order. Tell the tech what size barrel you want and how long you want the barrel to be and ask him if it will make weight.