u/Electronic-Page1499

Hi all, I'm wanting to knit a pattern that calls for isager soft (formerly eco soft) but the colour I want has been sold out since January so I'm now looking for alternative yarns. I've found Sandes Garn's Poppy which has a slightly different composition (50% superfine alpaca, 35% cotton,15% merino-wool) compared to isager softs (56% Alpaca, 44% Organic Cotton). Poppy's recommended needle size is 5.5-7 while isager softs is 5-6. Does anyone know how this will affect things and would this be an appropriate substitution?