A few years ago,I bought a fair amount of Mercruiser engine and drive parts from these guys in Florida(Go-fast).
I don't know a lot about their engine packages,but when I was thinking about a new package,I found their prices to be very good.They ship everywhere.
Can't vouch for the service on engine and drive packages,but their service on parts was very good.
These are list prices,but If I remember right the discounts were big.At the time I was thinking about the 383 stroker as well.They had a good price on it then as a package with the drive,but I only see the engine by itself now(last item).
http://www.go-fast.com/Mercury_Mercruiser_Engines.htm
http://www.go-fast.com/mercury_mercr...ine_Prices.ASP
As for that Worcester ma.place,I've also heard some not so good stuff about them,although you never know,maybe it wasn't a common occurence