What is the best level to do this?
This means strength + dex + ias, ideally high rolls
Affix level of high strength is 59, so 3/4 of character level the ilvl of this needs to be level 80 correct? So i'd have to be at elast 85 to gamble this?

no, you are mixing up terms. also forget the 3/4 thing, that is wrong...
ilvl, qlvl and mlvl determine alvl. alvl needs to be 59 (that is correct), qlvl depends on the base you gamble, ilvl for gambling is determined by clvl. so your desired clvl depends on the qlvl of the base

So lets say i gamble heavy gloves, and they upgrade to sharksin
Did i need to gamble these on a higher or lower level to get the affix, and for which?
Sorry extent of knowledge of this is based on arreat summit.