To lengthen or shorten sleeve for 3/4

Hello: I am making the jumprope. I want to do the tab sleeve, but I want it in a 3/4 option. We simply do not do long sleeves. She'd rather freeze and 3/4 is the longest I can get without a sensory issue. Anyway, the pattern for the long sleeve narrows as it goes down until a certain point and then about 3 inches before it ends it stops narrowing and straightens out- so you have enough fabric for the hem. The short sleeve with tab doesn't do that. You just cut straight across. The short sleeve- the sleeve narrows about 3/8" over the sleeves 8 inch length. I want a 3/4 sleeve with tab (so 11 inch final). The sleeve narrows about 3/4 inch over the 11 inches. So my question is do I just add the 1.5 inches (the cuff amount) from where I want it to end and cut (with a narrowing of about 1 inch in the sleeve), or do I mimic the bottom of the long sleeve and to the 1/5 inches straighten rather than narrow? Thoughts? Anyone done this before? Oh an a humorous side note. I had some lovely Liberty 1/2 yd cuts. I gave girlfriend an option for her "contrast" fabric- the sash, sleeve tabs, collar and yoke. She choose one. Looked at the other and said... I like that one very much too. So soft. Can you make me a dress out of that? LOL... good taste girly!- I am making myself a monster! ;)