Hi Dave,
I've got a set I picked up a couple of years ago, been a while since I looked at them but as I recall they are missing pump jets. I've never stripped them either so I'd imagine they are in need of a rebuild. Would need to take a look to see what venturis etc they have, but chances are they're not big enough for your 1776. So a change of venturis and jets would be in order.
If you're at all interested in this, let me know. You may be looking for an out-of-the-box solution.
We're in Ponthir near Newport so possibly not too far from you.
Cheers,
Rich