Honda K20 / K24 ok for the exxe, IMO not for the Scorpiacarlo as it is more of a Grand Touring car. Alternative power train is on the to do list for the Scorpiacarlo project..
Power train choice will be a Saab B234R in stock tune. OEM of 225 Bhp / 250 lb/ft torque about 3,000 rpm. Does not sound like much, until you've been around a B234 turbo for a few decades. The original Saab-Scania design and production engine was quite capable of twice that power output (450 bhp / 500 ft/lb of torque) with proven reliability on stock OEM internals.
They are famous for digesting gear boxes with a slight burp connected to them due to the torque they are easily capable of producing.... as this LeMons team discovered upon installing one of these into a Nissan 300ZX. The boost was upped, the Nissan gearbox became ground up metal bits.
http://www.roadkill.com/lemons-forget-ls-swaps-drop-turbo-saab-engine-z-car/
Does good in boats too.
"Hi! And thanks for all your comments. Sadly this summer went how it went. We weren´t able to get a correct Counter-stern so it was a no go. I´m trying to get one from the States this winter, so hopes are high for next summer. Turbos are now upgraded to TD04-15T´s
We are starting with approx 450hp with base-software. Cheers!"
The earlier Saab B202 (two liter, twin cam) was used in the barber Saab series with zero failures or problems from direct off the production line engines. This is extremely telling of Saab's engineering, design and production of these turbo engines.
https://www.eeuroparts.com/blog/7723/formula-cars-with-saab-engines-the-barber-saab-pro-series/
Then we have the Saab-Fiat-Lancia-Alfa Romeo connection..
Bernice