I just replaced the two old Gray 512 forward portlights with New Found Metals Trimatrix portlights. They appear substantially more robust that the originals and install in the old cut-out without sealant by through-bolting. The price is comparable to Pompanette/Gray ports.
You may wish to check out the user comments on the New Found Metals tri-matrix website. I feel the same and will replace the remaining flimsy and cracking
Gray ports asap.