73-74 140s, 164 and 1800ES were available in bright "international" or "safety" orange. I think there was a somewhat more muted orange for the first few years of the 240, but, like scorron said, I don't think they lasted beyond the 70s. His idea of buying one cheap, with peeling clearcoat, and having it repainted orange is probably the way to go. Try to find one with a black interior, as tan or blue would not go well with an orange car. Silver cars often had black interiors, and were prone to paint problems. Some maroon cars have black interiors, but the paint usually holds up well on these.

Look for an 88 or newer, to avoid wiring harness problems. 90 and up have an air bag, and some 91s and up have ABS, if those are important to you. 93s have improved air conditioning, compared to earlier models.