Where can l find details? These are ovely cars, they have great handling and roadhoaliding, but needed more power. Has anybody modified one or fitted different motor etc.?
l like the body style of the DS more than the SM, and l wonder if someone fitted motor and gearbox from CX or XM or SM in there?
l like the body style of the DS more than the SM, and l wonder if someone fitted motor and gearbox from CX or XM or SM in there?

Look up details about the Citroen SM. This is a DS but fitted with a powerful Masserati engine.

Probably ur best bet is to fit an injected lump from a CX, as it is essentially the same engine. Who knows, maybe the 2.5 turbo could be made to fit as well? If so, you've got access to 168bhp in standard form & about 200bhp if u chip the turbo. Fast enough for a 1960 is spec car, I'd have thought! If you're actually considering it, rather than just idly speculating, I'd try contacting one of the many specialist DS garages or the Citroen owners club.

Edit: Given that the Maserati motor from the SM is notoriously unreliable, hideously expensive to maintain, near impossible to get parts for, & only produced 170bhp (we're talking about a 1971 car, remember) I'd go with the CX unit, as it would be a much easier swap, much cheaper & is still in plentiful supply. Bear in mind that most CXs were scrapped for rust issues or general decrepitude rather than engine failure. The engines in these things can last over 250,000 miles.