Doesn't exactly answer your question, but any chance a Hanoverian pelham would work? A bit cheaper and used by a few in our barn that also went with a segunda snaffle. Still not cheap, and I suspect the same website where you found the segunda pelham. That guy does make many of his own bits and will let you exchange one bit for another if the first one doesn't work.
That is a very high port....I would be afraid to have just anyone ride in that. Not saying the OP is "anyone" but that is a helluvalota bit! If a horse has ANY tendency to get "light" in the front, I think this bit will encourage that behavior, ie, rearing.
I had a BIG dutch WB that was sooooo heavy (and 17 hands against my 4'10" frame). I think this woud have been a good bit for him, but a similar bit in a Kimberwick style caused rearing my my hackney. Both had equally hard mouths.
$375 is a lot of money. Ask your trainer if there are other pelham options with ports that perhaps would be acceptable.
The Pessoa line of bits has 3 pelhams with ports; a hanoverian type, a rubber covered high port and a "correction" pelham with a port.
These are all under $125 and are fairly easy to come by.