A 2.0 Pinto sounds the best thing for it at the minute.

A 24v would make you smile but the parts list would be long and it's an involved job.

Pinto with Weber carb would be more practical by the sounds of it.

Exhaust & fuel run down the opposite sides of the car though I think, but shouldn't be too hard to sort.

I've had countless CVH Sierra's over the years and thoroughly hated every single one of them. (not the cars)