Some of these 4 cylinder, liquid cooled motorcycle engines can be used in the conventional way by turning the engine 90 degerrs to put the output shaft to the rear. It would be necessary to use one that had the chain on the left, otherwise the shaft turns the wrong way.
Next, machine the teeth from the sprocket & use the resultant disc as a mounting face for the uni joint & the front drive shaft. Use the original gearbox mounting for a new crossmember that takes the driveshaft center bearing & run the rear driveshaft from there.

The engine will be offset in the chassis, but don't wory 'bout that, you will have bigger problems to handle. You will need to work out clutch actuation, gear lever mechanism, & of course, you will need to overcome the reverse gear problem.

After doing all this, you will likely find that the final drive ratio is still too low for such a high reving engine as motorcycles use a primary reduction. That is, the clutch [& gearbox input] spin at a speed that is slower than engine rpm. The clutch is geared down.

There is a racecar being built about 2 blocks away with a Kawasaki engine done this way & he had to build a "step up" box to bring drive shaft speeds up to allow the car diff to produce some speed.

After you have solved ALL the engineering & construction problems, spent a bucket of money, & wasted countless hours, you must take one good look at it all & ask yourself,.......why?