I would like to thank everyone who contributed to the discussion & shared their experiences. You gave me the impetus to do some real tests.
TEST 1 Ran older (90's) SRAM chain unknown model # with 42 -105bis and 52 - 93 rings on a Stronglight 93 crank It worked fine on the road no trouble changing up or down between rings.
TEST 2 Ran a modern SRAM chain PC-830 chain with 42 -105Bis and 52-93 rings on a Stronglight 93 crank This worked even better on the road, seemed smoother no trouble changing between rings!
TEST 3 Ran a SRAM chain PC-830 chain with 42 - 105Bis AND 52 - 105bis rings on a Stronglight 93 crank I had been convinced that this combo wouldn't work because of the additional separation between the teeth. Back in the 80's I had problems with the change getting stuck between rings when I tried to use the inner ring from a Stronglight 49D set on a 93 crank! So I very gingerly tested this configuration in the house just playing with the gear changes not actually riding the bike expecting the chain would get stuck between the chain rings! BUT It worked fine under NO-LOAD conditions! But would it work on the road? So throwing caution to the wind I went out for a test ride This unlikely combination worked WORKED FINE on the road.
No I didn't repeat this last test with the OLDER SRAM chain! I didn't want to tempt fate! Besides there was little point when the newest SRAM chain is smoother and thay are readily available.
FYI my test bike was a Peugeot PY10 with mid 70's Simplex SLJ derailleurs a Shimano 14-16-18-20-22-24-28 block on an English threaded Maillard 700 hub so is probably on topic!
Thanks Again Everyone for your help
Emerson Johnston
Kanata Ottawa Canada