A few pointers:
The trophy has a 5% skill mod, the same as a geerlock and they do NOT stack. When you get your trophy sell your geerlock.
The trophy is triv >250, probably 260 or so which means, what ever your skill, you will have at least a 1/3 chance of failing. You can try to make it with any skill level but the closer to 250 you are the better your chance. Note it is ONLY your current skill that matters when you try for your trophy and Int/Wis/Buffs make no difference whatsoever.
The maximum any unmodified basic tradeskill can reach is 250. If you are a GM with geerlock or trophy - it should make you 262 - but it doesn't, for some reason, the maximum modified skill is fixed at 252.
So, with a skill of 240 and a +5% mod, technically you have 252, the maximum possible skill. This means there is absolutely no benefit, apart from pride, in getting your skill over 240.
The title Grandmaster is reserved by most people for those who have an unmodified skill of 250. However, at 240+, it is common to refer to onself as a "Technical" GM