pt:

Gap is 0.6 mm or about 0.028", normal for "low" voltage coils (as used without electronic ignition).

Bosch plugs are fine, but if you want to use platinums you must use non-resistor wire. I'd stay with "plain" non resistor plugs if you do not have transistorized ignition. Bosch plugs willnot recover from carbon fouling, they have to be mechanically cleaned. NGK do not have this problem, otherwise they are very similar

Chances are you will have to order non-platinum plugs these days, seems that only platinums are readily available. Stands to reason, since they are MUCH better plugs, but only if they work well in your engine!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!