Having owned an MD1 which is (I imagine) roughly half of the 280 thousand KG quoted(!)...if you're buying and then transporting it'll help to remove the flywheel first. You'll need some hefty tools and bad language to loosen the nut and cam but it'll be much easier to lift and you'll be able to distribute the weigh in your van better.
Hi Richard - we changed an md11d for another one in our Maxi 100 last year - if our experiences are of any use to you send a private email and I'll give you a 'phone number. We fetched the alternative engine from Dundee in a VW estate.
From memory, circa 380lbs, of which the flywheel accounts for 80lbs. So take the flywheel off before doing anything else. I am looking forward to doing just that later this year when the Volvo goes to the place all Volvo's deserve - deep six.