David, I don't have the exact measurement handy, but it should be well over 7.5 feet.
Here is a (lousy) photo of an 8' Dyer
dinghy on the foredeck. This particular PSC 31 does not appear to have the forestay rigged, but we have the same mast pulpits (which extend forward of the mast) and the same
dinghy and we can put the
dinghy on deck without covering the deckplate for the forestay.
However, it can get a bit awkward with the
dinghy on the foredeck.
Also, if you like the boat, I wouldn't let the
dinghy drive the decision. There are other
dinghy solutions available...