Simplex Super LJ capacity?

[Handlerman]

I currently have the Simplex Super LJ front/rear system on my vintage Gitane TDF, with 52/42 (Stronglight 93) on front chainwheels and 24 through 10 on rear freewheel, but increasingly find myself in mountains with aging legs. What's the best possible combination for climbing that the throws and take-up will handle? Anyone remember or have some literature or experience?
Handlerman in Alaska