There's a couple of things you can do. The cheapest way is to open the ID of the seat up with the cutter as much as possible. This is just like going to a larger seat. That way you don't get charged for cutting a seat out, machining a new recess and press another one in. Then you can just run a 1.86I/1.60E valve with stock seats. These would work well.
The reason for not recommending a larger valve size is because the valve isn't the limiting factor, the ports are. The throat is about 75% the size of those valves. You need to be 90% of whatever valve size you run.