Dyform or not?

[Tim B]

I am about to replace the standing rigging on my Camper and Nicholson 30, its a 1973 masthead cruiser/racer. The mast has a pair of caps, one pair of lowers forestay, inner forestay and adjustable backstay.
The current wires are 7mm Dyform lowers and 6mm Dyform for the rest. This wire seems heavy to me and was wondering about using normal consruction wire to save cost. Having trawled the web I can not find an original rigging plan of the boat.

Should I be cautious and stick to Dyform at twice the price?

[matt the rigger]

Dyform is not necessary. 316 stainless 1x19 of the same diameter work just as well.