One option to consider is to add some thickness to your companionway doors in the area where the latch & handle are to be fitted, so that there's plenty of wood to take the mortise for the hardware & still have adequately thick doors once it's fitted. This would make choosing hardware a lot easier than at present. And likely would get your problems solved
for far less than $325. As at that figure you might even look into semi-custom hardware.
The other option is to shop around a bit at 2nd hand chandleries. As it's common to find hardware there for pennies on the dollar. And many of them will either assist you with shopping
in real time, long distance, via a phone
call. Where they'll look through their stocks while talking with you. Sometimes to include adding a video link via computer when several possible hardware options are found. Along with the sales person's measuring it's key dimensions, etc.
Plus some outfits have their inventories computerized as well, including manufacturer's part numbers, sizes, & item quality. Along with pics, & spec's.
Option 3 would be the McGuyver route
. Either fixing the old, or cobbling together something.
Which, BTW, is there a way to find out what happened to the current
unit to render it unservicable, & or unrepairable? And are you certain as to what the original configuration was? Given that there are usually a number of hardware configurations that will suffice.
To a large degree it's a question of time vs. money
(& ingenuity). Plus, like Schooner Chandlery
has aluded to, there are multiple hardware options that are more than viable.