I think that'd be the easiest, fastest way too. Get a triple crank (Deore, etc) with the common 110/74bcd combo and get whatever rings you like, to run it as a compact double. That way the front derailleur could stay; just mounted a little further down the seat tube. Popular big/small ring combos on a compact double include 46/30, 50/34, etc.
I can't say for sure, but that rear derailleur looks like it would handle the existing freewheel with those compact chainring combos quite easily. A shorter chain would likely be called for, but you want to replace that rusty old thing anyway.
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● 1971 Grandis SL ● 1972 Lambert Grand Prix frankenbike ● 1972 Raleigh Super Course fixie ● 1973 Nishiki Semi-Pro ● 1979 Motobecane Grand Jubile ●1980 Apollo "Legnano" ● 1984 Peugeot Vagabond ● 1985 Shogun Prairie Breaker ● 1986 Merckx Super Corsa ● 1987 Schwinn Tempo ● 1988 Schwinn Voyageur ● 1989 Bottechia Team ADR replica ● 1990 Cannondale ST600 ● 1993 Technium RT600 ● 1996 Kona Lava Dome ●
Last edited by Lascauxcaveman; 06-26-17 at 12:57 PM.