The front hatch is a Bowmar. It IS available from Pompanette. Price is an inch short of a heart attack!
A great welder can weld cast aluminum. I had a TORO cast aluminum lawnmower welded when it found a brick in a neighbor's lawn. It's still holding up perfectly.
If you decide to repair check the lens carefully. Mine has a few cracks around the mounting holes I thought would seal with the silicone. I DO get a few drops in a big rain. Just on my HEAD! There is a company in the magazines that will replace the lens with a new one.
You can cut the LEXAN yourself to make a replacement.
I'd try to repair with replacement as a costly back-up.
Good Sailing in that beautiful 323!!!!!