Shame on you more 'senior' folks for giving Dom such a hard time (though it did make me smile...), and shame on you, Dom, for a post that has more than a whiff of a troll about it... yes? no?

Anyway, most folks in this situation wouldn't waste time and effort and money on the route you suggest. If you are serious about completing the Scooby transplant then *any* resources spent on something that is not directly focused on that is so much resource wasted, be that time, money, favours from friends or whatever.
You should devote *all* your resource to completing the Scooby. If this requires that you obtain some alternative mode of transport, then do just that. Go by bus. Get a bike. Get a motorbike. Get another car that's cheap to run and reliable.
But if you divert to another engine transplant, *that* will become your project, and the Scooby idea will fall by the wayside. You will never return to it.
Why? Because faced with the NEED to fix the 'new' engine transplant (so you can actually get from A to B), as against the mere WISH to work on the Scooby (because that isn't essential, it's only a dream), the 'new' engine will ALWAYS take priority. Result is you will always be working on the new engine, and never on the Scooby.
I caveated this by saying "if you are serious about the Scooby project...". I wonder if in fact you're actually having second thoughts about it, and would welcome a change of direction to something less ambitious and more readily achievable?
If that's not the case then please don't be offended, but if it is the case, you wouldn't be the first, I've been down that road more than a few times myself, and you certainly won't get any stick from me over it, and I would hope nor from other members who have been, perhaps, shall we say, not so forgiving of your ambitions in the past

The ideas suggested by Piotr sound very interesting, and probably well worth investigating in more detail. Back in the day, I got the engine/transmission unit out of an 850 Sport hoping to transplant it into my 500 Giardiniera... as others have found before me, "life" got in the way (though not having a garage didn't help much either!) and ultimately both went to that great car park in the sky...