have you checked with a local small engine shop to see what new style carbs will fit that old engine. Any good shop should want to help you cross ref that carb. I know mine will. He's a small business and his prices may be a little higher but i've heard from a company as big as Exmark saying he is the best in my area.
Just my .02 worth. It may be worth less to you, but hey it's only 2 cents.