The deal comes down to a couple of odd factors.
The BEST thing about a Europa is the suspension design. It's an awesome handler.
The problem with the suspension is that the transmission is part of it. That's not a misprint. The rear suspension of a Europa uses the transmission case as a connecting point. Of course, these transmissions were questionable, and can't take huge power. There is also very little they will mate to. The minute you do a motor or transmission swap, you've lost the rear suspension, and don't even have a roller. Yes, you can fabricate something new. But it's no longer the Lotus suspension.
Then comes the structure. The chassis is the strength, the body is nothing. I really mean nothing- it's so thin I can lift the entire body myself if I get in the right position to balance it properly. It has a fiberglass pan, so you can't add a rollbar/ cage without adding structure. They were wonderfully light, but nightmarishly frightening from a safety perspective. If you correct the safety, you may double the weight of the car, and loose it's nimbleness.
Next comes the motor position. The chassis is a spine down the middle, that Vees behind the driver's seat to pick up the rear wheels. The engine tucks into the V. There are very few engines that will fit in that vee and still give you enough space for a drivetrain to drive the rear wheels. Yes, you can fabricate, but again you will loose the Europa-ness.
Lots of other oddities- for example, the firewall is cardboard (again, no exaggeration). Good luck getting it through tech with no fire separation from the engine to the passenger compartment. Yep. you can fabricate. Yep, it will add weight again.
The windshield is made of unobtanium, and is worth more than the car. So, many in mediocre cars are sacrificed for the few remaining good Europa restorations, which makes the remainders less valuable.
The list goes on and on. The car was a really neat concept in it's original form, but is challenging to make serviceable in an afterlife.
And if you are just going to drop a body on a Locost, there are better bodies.