1974-75 Opel Ascona engine swaps?

Well, I found an Opel Ascona with a good transmission,body and interior, but the engine isn't in it, and was blown anyway. Anyway, what's a good candidate for an engine swap into an Ascona? I am kind of looking at the 2.2 or 2.5L Chrysler turbo engines, or an RX7 13b turbo rotary. However, what's a good candidate for an engine to go into this? I've heard the Eco-engines do good, but I have no idea what they are or anything else about them. Any ideas on anything?